Multi-lumen extrusion tubing

ABSTRACT

A multi-lumen balloon for use in a fluted balloon centering catheter and method for providing the same. The multi-lumen balloon maintains a radiation source at the center of a cardiovascular artery, has improved blood perfusion capability, and has improved balloon refolding characteristics. The method of fabricating a multi-lumen balloon designed for a radiation centering catheter uses an improved extrusion process that allows the manufacture of the multi-lumen balloon sub-assembly to be done separately from the catheter shaft assembly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to medical catheters and more particularlyto a multi-lumen balloon for a radiation centering catheter.

2. Description of Related Art

Medical catheters generally include elongate tube-like members that maybe inserted into the body, either percutaneously or via a body orifice,for any of a wide variety of diagnostic and interventional purposes.Such catheters are particularly useful with regard to certaincardiovascular applications where the object is to deliver a treatmentor instrument to a remote lesion.

Percutaneous Transluminal Coronary Angioplasty (PTCA or balloonangioplasty) is the predominant treatment for coronary vessel stenosis.In PTCA, catheters are inserted into the cardiovascular system via thefemoral artery under local anesthesia. A pre-shaped guiding catheter ispositioned in the coronary artery, and a dilatation catheter having adistensible balloon portion is advanced through the guiding catheterinto the branches of the coronary artery until the balloon portiontraverses or crosses a stenotic lesion. The balloon portion is theninflated with a medium to compress the atherosclerosis in a directiongenerally perpendicular to the wall of the artery, thus dilating thelumen of the artery. Patients treated by PTCA procedures, however,suffer from a high incidence of restenosis, i.e., the same area of thecoronary vessel collapses or becomes obstructed.

Recent preclinical and early clinical studies indicate thatintervascular radiation after balloon angioplasty can reduce the rate ofrestenosis caused by intimal hyperplasia. Generally, in an intervascularradiotherapy procedure, a flexible catheter is inserted into thecardiovascular system of a patient and then advanced to the region ofthe vessel that has been subjected to the angioplasty procedure. Aradiation source or a treatment catheter having a radiation sourceinside it is then advanced through the flexible catheter so that theradiation source reaches the stenosed vascular site and can deliver aneffective dose of radiation. After the radiation treatment, the catheterand radiation source are removed.

Because for a given radiation source activity, the intensity of theradiation delivered to a vessel wall varies in inverse proportion to thesquare of the distance between the radiation source and the vessel wall,it is desirable to hold the radiation source at, or reasonably near, thecenter of the vessel for a given treatment period. If the source is notcentered within vessel, the vessel wall nearest the source may receivean excess of radiation, while the portion of the vessel wall farthestfrom the source may be underexposed to the radiation.

There are a number of ways to center a radiation source within a vessel.One such way is using a spiral balloon having a central lumen in whichthe radiation source is advanced to the stenosed vessel site. In aspiral balloon catheter, the balloon is wrapped or molded in a spiralfashion around a flexible centering lumen. When inflated, the balloonouter diameter pushes against the vessel walls while the inner balloondiameter pushes the radiation source lumen toward the center of thevessel.

Spiral balloons have several significant drawbacks when used inintervascular radiotherapy to control restenosis. The first drawback isthat because the balloon is wrapped or molded in a spiral shape aroundthe centering lumen of the catheter, the centering effect of theradiation source decreases as the pitch of the turns of the spiralballoon increases. Thus, the fewer turns a spiral balloon has in itsconfiguration, the less centered the radiation source is inside thevessel. Also, if the spiral balloon is over-pressurized, it will loseits spiral shape, thus leading to inconsistent centering of theradiation source. Another drawback with a spiral balloon is that becauseevery spiral is a taper, when the balloon is in a deflatedconfiguration, it creates a stiff catheter with a bulky balloon. Thisleads to poor access and limits the use of spiral catheters to certainportions of the vascular system. Furthermore, at the end of theintervascular radiation procedure, the tapers create poor refold of thespiral thus making the removal of the balloon catheter difficult for thephysician. Another significant disadvantage of using a spiral balloon inintervascular radiation is the spiral balloon's inconsistent bloodperfusion ability. Good blood perfusion of the vessel is achieved onlywhen the blood is flowing freely through the spiral cavity created bythe balloon. If any portion of the spiral cavity is blocked, then theflow of the blood is also stopped at that point. Thus, blood perfusionmay not be adequate.

Another way to center a radiation source within a vessel is to use asegmented balloon catheter having a series of peaks and valleys createdby segmenting an ordinary balloon catheter. The segmented ballooncenters the centering lumen using the same principle as the spiralballoon catheter.

An additional way to center a radiation source within a vessel is byusing a catheter having an outer balloon and an inner balloon disposedwithin the outer balloon. Generally, the inner and outer balloons arepositioned parallel to each other and axially with the catheter shaft.The inner and outer balloons may have a spiral or a segmentedconfiguration. The inner centering balloon may also be a multiple axiallumen balloon, where the lumens extend parallel to the catheter shaft.

Another way to center a radiation source within a vessel is by having aballoon attached to the distal portion of a radioguide catheter. Wheninflated, the balloon engages the walls of the vessel to center thetreatment channel. The balloon may also be configured to include spirallumens or/and perfusion lumens to permit perfusion of the blood when theballoon is inflated.

Segmented balloon catheters and multiple balloon catheters have many ofthe same drawbacks as those associated with spiral balloon catheters,including inadequate centering of the radiation source, poor balloonrefold, catheter stiffness, bulky balloon configuration, inconsistentperfusion, etc. While balloons configured with spiral lumens orperfusion lumens have a better perfusion capability than single-spiral,segmented, or multiple balloon configurations, they still have somedisadvantages, including poor balloon foldability, catheter stiffness,and less than optimal perfusion capability.

Currently, most radioguide centering catheters used in the industry areof the type known in the industry as “tip RX” (RX being “rapidexchange”). Tip RX radioguide centering catheters are characterized by ashort guidewire riding length of approximately 5 mm and a guidewire exitnotch distal to the centering balloon. Tip RX catheter assemblies haveseveral disadvantages when used in vascular radiation therapy. First,the trackability of the catheter is not consistent in a challengingvascular anatomy, and can go from excellent to poor for no apparentreason. Poor catheter trackability may make it impossible to place thecatheter at the desired treatment site, preventing delivery of theradiation therapy. Pushability is similarly problematic with the tip RXcatheter. When withdrawing a tip RX catheter, it is also possible toprolapse the guidewire, complicating the procedure. Another disadvantageis that because the guidewire lumen is distal to the balloon, it addsapproximately 10 mm to the overall length of the tip. Cardiologistshowever, prefer to have the tip of the catheter as short as possible inorder to prevent potential injury to the artery distal to the treatmentsite. Another disadvantage of using a tip RX balloon catheter forvascular radiation therapy is that since the exit notch is distal to theballoon, the guidewire must be left in place, thus creating a small butmeasurable shadow in the radiation dosimetry.

In addition to tip RX balloon catheters, other catheter designs used forvascular radiotherapy employ an “over-the-wire” (“OTW”) guidewire lumenconfiguration. Currently, these OTW radiation delivery catheters do notprovide the capability of centering the radiation source. Furthermore,while an over-the-wire configuration catheter assembly allows for theguidewire to be pulled back during radiation delivery, the guidewirelumen shifts the source away from the center of the catheter, thusmaking the centering of the radiation source even more problematic.

The manufacture of inflated balloons with diameters in a range ofapproximately 1.0 to 6.0 millimeters (mm) presents another significantissue with current balloon catheter designs. One of the challengesrelates to the stiffness of the balloon. For example, some manufacturershave used several separate small diameter balloons and attached themusing glue or other bonding material around a central catheter shaft toform a balloon catheter. Because the glue or bonding material ispositioned along the catheter shaft, the catheter is stiff and difficultto use in coronary vessels having tortuous paths. Therefore, this designconfiguration gives sub-par performance. Others have used an extrusionprocess to manufacture a multiple balloon radiation centering catheter.During the extrusion process, however, excess material is generatedwhich tends to make the catheter stiff. In addition, because thematerial used for the radiation source lumen has generally beendifferent than the material used for the guidewire lumen or thecentering balloons, the extrusion process is extremely difficult tocomplete successfully.

SUMMARY OF THE INVENTION

A multi-lumen tubing and method of manufacturing the same is described.The multi-lumen tubing includes a tubing body having a central lumen anda plurality of outer lumens disposed around the central lumen. Theplurality of outer lumens are coupled with the central lumen by a sharedwall. The multi-lumen tubing also includes an undercut region disposedthe central lumen and the plurality of outer lumens.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the accompanying figures:

FIG. 1 is a side view of one embodiment of a multi-lumen fluted ballooncatheter assembly for centering a radiation source, with guidewire lumenextending through one of the outer lumens of the balloon.

FIG. 2 is a cross-sectional view of the multi-lumen fluted ballooncatheter assembly of FIG. 1 taken along line A—A.

FIG. 3 is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 1 taken along line B—B.

FIG. 4 is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 1 taken along line C—C.

FIG. 5 is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 1 taken along line D—D.

FIG. 6 is a side view of a second embodiment of a multi-lumen flutedballoon catheter assembly (standard-RX configuration) for centeringradiation source, with proximal and distal slideable seals and without aguidewire lumen.

FIG. 7 is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 6 taken along line E—E.

FIG. 8 is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 6 taken along line F—F.

FIG. 9 is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 6 taken along line G—G.

FIG. 10 is a side view of a third embodiment of the multi-lumen flutedballoon catheter assembly (for a tip-RX configuration) for centering aradiation source.

FIG. 11 is a cross-sectional view of the multi-lumen fluted ballooncatheter assembly of FIG. 10 taken along line H—H.

FIG. 12 is a partial longitudinal cross-sectional view of themulti-lumen fluted balloon catheter assembly of FIG. 10 taken along lineJ—J showing a configuration for inflation/deflation and attachment.

FIG. 13 is a side view of an third embodiment of a multi-lumen flutedballoon catheter assembly (for a standard- RX configuration) forcentering a radiation source, where the guidewire lumen and source lumenextend through catheter inner member and central balloon lumen.

FIG. 14 is a cross-sectional view of the multi-lumen fluted ballooncatheter assembly of FIG. 13 taken along line K—K showing a guidewirelumen extending through balloon central lumen.

FIG. 15 is a cross-sectional view of the multi-lumen fluted ballooncatheter assembly of FIG. 13 taken along line L—L showing guidewirelumen, radiation source lumen, and inflation/deflation lumen withincatheter inner member.

FIG. 16 is a cross-sectional view of the multi-lumen fluted ballooncatheter assembly of FIG. 13 taken along line M—M showing guidewirelumen and radiation source lumen.

FIG. 17 is a schematic side view of the proximal and distal balloon sealareas for the fluted balloon radiation centering catheter assembly ofFIG. 1.

FIG. 18 is a cross-sectional view of a four-lumen balloon for acentering catheter assembly.

FIG. 19a is a cross-sectional view of the four-lumen balloon for acentering catheter assembly with two balloon outer lumens flattened forproximal balloon seal preparation.

FIG. 19b is a cross-sectional view of the four-lumen balloon for acentering catheter assembly with a configuration for folding the twoballoon outer lumens flattened for balloon proximal seal preparation.

FIG. 19c is a cross-sectional view of the four-lumen balloon for acentering catheter assembly with another configuration for folding thetwo balloon outer lumens flattened for balloon proximal sealpreparation.

FIG. 20a is a cross-sectional view of a configuration for a completedballoon proximal seal for a four-lumen balloon.

FIG. 20b is a cross-sectional view of a second configuration for acompleted balloon proximal seal for a four-lumen balloon.

FIG. 20c is a cross-sectional view of a third configuration for acompleted balloon proximal seal for a four-lumen balloon.

FIG. 20d is a side view of a “football-shape” cross section mandrel usedto perform the proximal seal for a multi-lumen balloon.

FIG. 21a is a schematic side view of the distal balloon seal area forthe multi-lumen fluted balloon radiation centering catheter assembly ofFIG. 1.

FIG. 21b is a schematic side view of the tip-forming sheath for formingthe tip of balloon distal seal for the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 1.

FIG. 21c is a schematic side view of the first and second heat shrinktube materials used for the balloon distal seal.

FIG. 21d is a schematic side view of the source mandrel having a taperedlength.

FIG. 21e shows schematic side, top and bottom views of the sourcemandrel having a ramp length.

FIG. 22a is a cross-sectional view of a basic four-lumen (quad-lumen)extrusion tubing with “shared wall” and “fillet radius” regions.

FIG. 22b is a cross-sectional view of a tip and die assembly used tomake the quad-lumen extrusion tubing of FIG. 22a.

FIG. 23a is a cross-sectional view of a second embodiment of aquad-lumen extrusion tubing with “shared wall” and “undercut” regions.

FIG. 23b is a cross-sectional view of a tip and die assembly used tomake the quad-lumen extrusion tubing of FIG. 23a.

FIG. 24a is a cross-sectional view of a third embodiment of a quad-lumenextrusion tubing with “shared wall” and “undercut” regions.

FIG. 24b is a cross-sectional view of a tip and die assembly used tomake the quad-lumen extrusion tubing of FIG. 24a.

FIG. 25a is a cross-sectional view of a fourth embodiment of aquad-lumen extrusion tubing with “standoffs” regions.

FIG. 25b is a cross-sectional view of a tip and die assembly used tomake the quad-lumen extrusion tubing of FIG. 25a.

FIG. 26 is a flow chart illustrating a method of manufacture amulti-lumen balloon assembly of the present invention.

FIG. 27a is a side view of another embodiment of a multi-lumen flutedballoon catheter assembly for centering radiation source, with twoadditional guidewire exits in the catheter shaft and guidewire extendinglongitudinally outside the balloon.

FIG. 27b is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 27a taken along line A—A.

FIG. 27c is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 27a taken along line B—B.

FIG. 27d is a cross-sectional view of the multi-lumen fluted balloonradiation centering catheter assembly of FIG. 27a taken along line C—C.

DETAILED DESCRIPTION OF THE INVENTION

A multi-lumen balloon for use in a fluted balloon centering catheter andmethod for providing the same is described. The present invention is amulti-lumen balloon for a radiation centering catheter that maintains aradiation source at the center of a cardiovascular artery, has improvedblood perfusion capability, and has improved balloon refoldingcharacteristics. The present invention also provides an improved methodof manufacture for a multi-lumen balloon design for a radiationcentering catheter, where such method allows the manufacture of themulti-lumen balloon sub-assembly to be done separately from the cathetershaft assembly. Furthermore, the present invention is a multi-lumenballoon centering catheter assembly with an improved guidewire designand method for providing the same. In addition, the present inventionprovides improved proximal and distal balloon seal designs and method ofmanufacture for the same.

In the following detailed description, numerous specific details are setforth in order to provide a more thorough understanding of the presentinvention. However, it will be apparent to those skilled in the art towhich this invention pertains that the present invention may bepracticed without these specific details. In other instances, well-knowndevices, methods, procedures, and individual components have not beendescribed in detail so as not to unnecessarily obscure aspects of thepresent invention. The present invention is a multi-lumen fluted balloonradiation centering catheter. FIG. 1 shows an embodiment of themulti-lumen fluted balloon centering catheter assembly 1 of the presentinvention that includes a multi-lumen balloon 10 and an interventionalcatheter 2 disposed at the proximal end of the balloon 10.

Balloon 10 includes a central lumen and a plurality of outer lumens (orlobes) disposed around the central lumen. The outer lumens areintegrally coupled with the central lumen so as to form the multi-lumenballoon. It should be noted that although the multi-lumen balloonconfigurations illustrated and discussed hereafter make reference to afour-lumen balloon configuration (i.e., balloon with a central lumen andthree outer lumens), the multi-lumen balloon of the present invention isnot limited to this four-lumen balloon arrangement. As it will bedescribed in the later sections, for some treatment applications and/orvessel treatment area configurations, using a three-lumen balloon havinga central lumen and two outer lumens may be desirable. In addition, forsome applications, having a balloon with more than four lumens may bedesirable.

The interventional catheter 2 used with the multi-lumen balloon 10 maybe one of several configurations known in the art, including a standardRapid Exchange (“RX”) design (as shown in side views in FIGS. 1 and 13)where a guidewire lumen 21 passes through the balloon 10 and exitsproximal to the balloon 10; a tip (or distal) RX design (as shown in aside view in FIG. 10) where a short guidewire lumen 21 is provided at adistal tip of the balloon 10; or an over-the-wire (“OTW”) design wherethe guidewire lumen 21 extends the full length of the fluted ballooncatheter assembly 1, including the multi-lumen balloon 10 andinterventional catheter 2.

Multi-lumen Balloon

Referring to FIG. 18, a cross sectional view of one embodiment of amulti-lumen balloon 10 for treating a body vessel 16 in the vascularsystem is shown. Balloon 10 includes a central lumen 12 and a pluralityof outer lumens (or lobes) 1 1 disposed around the central lumen 12. Theouter lumens 11 are integrally coupled with the central lumen 12 so asto form the multi-lumen balloon 10. Each of the balloon outer lumens 11has an inner radial length (or diameter) 18 and an outer diameter 15,defining balloon outer lumen walls 17. The walls 17 of balloon outerlumens 11 are made very thin to allow proper inflation and deflation ofouter lumens 11. The thickness of the walls 17 ranges from {fraction(0.5/1000)} in. to about {fraction (3/1000)} in. In one embodiment, wall17 has a thickness of {fraction (0.75/1000)} in.

The balloon outer lumens 11 can be extruded with either equal diameters15 (as shown in FIG. 18, and FIGS. 3 and 11) or with unequal (i.e.,asymmetrical, lopsided, etc.) diameters 15 (as shown in FIG. 14). Theballoon outer lumen has a diameter 15 sized in a range of approximately0 mm (no balloon lumen) to about 5 mm.

The balloon central lumen 12 has an inner diameter 18 a. The centrallumen 12 is capable of containing a radiation source (with or without aradiation source lumen) therein. The diameter 18 a of the ballooncentral lumen 12 is sized based on the radiation source outer diameter,for example a radiation source wire having an outer diameter in a rangeof approximately {fraction (10/1000)} in. to {fraction (50/1000)} in. Itshould be noted that the balloon central lumen diameter 18 a may be madesmaller than {fraction (18/1000)} in. for intervascular radiationtreatments using radiation sources having a diameter smaller than{fraction (10/1000)} in. or for radiation sources having a liquidconfiguration.

Continuing with reference to FIG. 18, the multi-lumen balloon 10 of thepresent invention is used in a fluted balloon radiation centeringcatheter assembly 1 for treating a body vessel 16 in the vascularsystem. Given the very small diameter of these body vessels 16, thecombined balloon diameter 13 (as measured across all balloon outerlumens 11 while balloon is in an inflated or deployed state) is kept ina range of approximately 1.5 mm to 6 mm for coronary vessels and in arange of approximately 3 mm to 12 mm for peripheral vessels. In oneembodiment (shown in FIG. 3), the combined diameter 13 is in a range ofapproximately 1.5 mm to 4 mm.

Referring now to FIG. 3, another embodiment of the multi-lumen balloonof this invention includes a balloon 10 having a central lumen 12 andthree outer lumens (or lobes) 11 disposed around the central lumen 12.The outer lumens 11 are integrally coupled with the central lumen 12 soas to form the multi-lumen balloon 10. Balloon 10 has a guidewire lumen21 extending lengthwise through one of the balloon outer lumens 11. Theguidewire lumen 21 is capable of receiving a guidewire 45 forpositioning the multi-lumen balloon 10 (and thus the radiation centeringcatheter 1) within a body vessel 16. The balloon central lumen 12 iscapable of containing a radiation source 25 (with or without a radiationsource lumen 22) therein. If a radiation source lumen 22 is used withthe radiation source 25 in the balloon central lumen 12, the radiationsource lumen 22 would extend lengthwise through the central lumen 12.

It should be noted that the multi-lumen balloon embodiment shown in FIG.3 is also adapted for receiving the guidewire lumen 21 (with a guidewire45) through its central lumen 12. In this configuration, since theballoon central lumen 12 would contain both a radiation source 25 (withor without a radiation source lumen 22) and a guidewire lumen 21, thecentral lumen 12 may take an egg-like shape. The inner diameter 18 a ofthe egg-shaped central lumen 12 would be sized based on the diameter ofthe radiation source 25 (with its radiation source lumen 22 if one ispresent) and the diameter of the guidewire lumen 21. In thisconfiguration, the diameter 18 a of the balloon central lumen 12 issized based on the radiation source outer diameter, for example aradiation source wire having an outer diameter in a range ofapproximately {fraction (10/1000)} in. to {fraction (50/1000)} in., andthe guidewire lumen diameter. Thus, the diameter 18 a may be in a rangeof approximately {fraction (10/1000)} in. to {fraction (75/1000)} in. Inone embodiment, the diameter 18 a is {fraction (62/1000)} in.

With reference to FIG. 4, for the four-lumen balloon embodiment shown inFIG. 3, three separate inflation lumens (54 b, 55 b) positioned proximalto the balloon 10 in a catheter shaft 41 are used to inflate the threeballoon outer lumens 11. The inflation lumens (54 b, 55 b) communicatedirectly with each of the balloon outer lumens 11. A common inflationlumen 36, positioned within the catheter shaft outer member 46 (shown inFIG. 5), provides a common communication path between the inflationlumens (54 b, 55 b) (and thus the balloon outer lumens 11) and aninflation port 33 (shown in FIG. 1) to which a balloon inflation means(not shown) is attached. In this configuration, an inflation medium 18 benters the balloon catheter assembly at the inflation port 33, passesthrough the common inflation lumen 36 onto the three balloon inflationlumens (54 b, 55 b), and then enters and inflates the outer lumens 11which causes the radiation source lumen 22 (and/or radiation source 25)to be centered within the :body vessel 16. The outer lumens 11 may beinflated at an operating pressure in the range of approximately 0.5-14atmospheres. In one embodiment, the outer lumens 11 may be inflated atan operating pressure in the range of approximately 2-5 atmospheres.

For the multi-lumen balloon shown in FIG. 3, the central lumen 12 doesnot have to be pressurized and may not have to be sealed in order toinflate the balloon outer lumens 11. It should be noted that havingindividual inflation lumens for each of the balloon outer lumens allowseach balloon outer lumen to be inflated to different pressures. Thismulti-lumen balloon arrangement is desirable for vessel treatmentapplications where the particular body vessel (in the area beingtreated) may not be fully circular (i.e., body vessel area may containcertain obstructions or “deposits” along its walls).

It should also be noted that it is not necessary to have individualinflation lumens (54 b, 55 b) for each of the balloon outer lumens 11 inorder to center to radiation source lumen 22 with the vessel 16. Forballoon designs where individual inflation lumens (54 b, 55 b) areabsent, a catheter shaft inner lumen 41a may serve as a common inflationlumen for the balloon outer lumens 11.

Continuing with reference to FIG. 3, the diameter 18 a of the ballooncentral lumen 12 is sized based on the radiation source outer diameter,for example a radiation source wire having an outer diameter in a rangeof approximately {fraction (10/1000)} in. to {fraction (50/1000)} in.The combined balloon diameter 13 (as measured across all balloon outerlumens 11 while balloon is in an inflated or deployed state) is kept ina range of approximately 1.5 mm to 6 mm for coronary vessels and in arange of approximately 3 mm to 12 mm for peripheral vessels. For theembodiment shown in FIG. 3, a balloon having a combined diameter 13 in arange of approximately 1.5 mm to 4 mm is advantageous when treatingcoronary vessels.

Referring to FIG. 11, another embodiment of the multi-lumen balloon ofthis invention is a balloon 10 having a central lumen 12 and a pluralityof outer lumens 11 disposed around the central lumen 12. The outerlumens 11 are integrally coupled with the central lumen 12 so as to formthe multi-lumen balloon 10. Bores (or channels) 35 are formedbetween;the outer lumens 11 and the central lumen 12. This arrangementallows an inflation medium 18 b to pass from the balloon central lumen12 into the outer lumens 11 and inflate outer lumens 11, causing aradiation source lumen 22 to be centered within a body vessel 16. Inthis configuration, the central lumen 12 may have to be pressurized inorder for the outer lumens 11 to properly inflate and center theradiation source lumen 22 within the body vessel 16.

For the balloon configuration shown in FIG. 11, the balloon centrallumen 12 is capable of containing a radiation source 25 (with or withouta radiation source lumen 22) therein. The multi-lumen balloon embodimentshown in FIG. 11 is adapted for receiving a guidewire lumen (with aguidewire) through either one of its balloon outer lumens 11 or throughits central lumen 12. Because in FIG. 11 the balloon 10 is shown asbeing used with a tip (or distal) Rapid Exchange catheter type (i.e.,the guidewire is positioned distal to the balloon), for the balloonembodiment of FIG. 11, the guidewire does not extend through any of theballoon lumens 11.

It should be noted that while the balloon configuration of FIG. 3 showsa guidewire lumen 21 (with guidewire 45) extending through one of theballoon outer lumens 11, the guidewire 45 (with or without its guidewirelumen 21) may also be positioned so that it extends through the centrallumen 12 of the multi-lumen balloon 10 (as shown in the balloonconfiguration of FIG. 14). Furthermore, whether a guidewire (and aguidewire lumen) extends through the multi-lumen balloon depends on anumber of considerations, such as the type of catheter used, the ballooncatheter manufacturing preferences, the treatment site configuration,etc. For example, when considering the type of catheter to be used, fora standard Rapid Exchange or an OTW catheter type, the guidewire 45(with or without a guidewire lumen 21) would extend through one of theouter lumens (as shown in FIGS. 3, 6, and 17) or through the centrallumen (as shown in FIG. 14). For balloon catheter assemblies using a tip(or distal) Rapid Exchange catheter type, because the guidewire (with orwithout a guidewire lumen) is positioned distal to the balloon, theguidewire would not extend through any of the balloon lumens (as shownin FIG. 11).

As with the other two balloon arrangements discussed above, for theballoon embodiment shown in FIG. 11 (i.e., having a “tip” or distalguidewire lumen that does not extend through the entire balloon lumen),the diameter 18 a of the balloon central lumen 12 is sized based on theradiation source outer diameter, for example a radiation source wirehaving an outer diameter in a range of approximately {fraction(10/1000)} in. to {fraction (50/1000)} in. For the balloon embodimentshown in FIG. 14 (i.e., where the guidewire lumen 21 is positioned sothat it extends through the central lumen 12), the diameter 18 a of theballoon central lumen 12 is sized based on the radiation source outerdiameter and the diameter of the guidewire lumen 21. Thus, the diameter18 a may be in a range of approximately {fraction (10/1000)} in. to{fraction (75/1000)} in. In one embodiment, the diameter 18 a is{fraction (62/1000)} in.

Continuing with reference to FIG. 11, the combined balloon diameter 13(as measured across all balloon outer lumens 11 while balloon is in aninflated or deployed state) is kept in a range of approximately 1.5 mmto 6 mm for coronary vessels and in a range of approximately 3 mm to 12mm for peripheral vessels. For the embodiment shown in FIG. 11, aballoon having a combined diameter 13 in a range of approximately 1.5 mmto 4 mm is desirable when treating coronary vessels.

Referring now to FIG. 17, a four-lumen balloon 10 having a guidewirelumen 21 extending through one of the balloon outer lumens 11 is shown.Note that one of the outer lumens is hidden from view. A radiationsource lumen 22 (capable of holding a radiation source) extendslengthwise through the balloon central lumen 12. The outer lumen 11 withthe guidewire lumen 21 extending through it is also inflated as part ofthe function of the centering balloon catheter.

Continuing with reference to FIG. 17, the multi-lumen balloon 10 has adistal seal 28 and a proximal seal 29. Distal seal 28 seals theplurality of distal ends 34 b of the balloon outer lumens 11 to acatheter shaft (formed by the radiation source lumen 22 and guidewirelumen 21) while the proximal seal 29 seals the plurality of proximalends 34 a of the balloon outer lumens 11 to the catheter shaft. Thedistal and proximal seals (28, 29) may each have a width in a range ofapproximately 0.5 mm to about 5 mm.

When balloon outer lumens' distal and proximal ends (34 b, 34 a) aresealed together into the distal seal and proximal seal respectively (28,29), each of the outer lumens 11 takes the form of a “flute” (i.e., anelongated cylinder having tapered ends) when inflated by an inflationmedium. The fluted balloon configuration shown in FIG. 17 isrepresentative of balloon configurations of this invention (as shown inballoon catheter assemblies of FIGS. 1, 6, 10, and 13).

Referring to FIG. 1, a treatment area 30 is defined between theballoon's distal seal 28 and proximal seal 29. The longitudinal lengthof the balloon treatment area 30 is made to be appropriate for the bodyvessel to be treated (for example, coronary vessels or peripheralvessels) and for the radiation treatment to be delivered. In oneembodiment of the present invention, the balloon treatment area length30 is in a range of approximately 18 mm to 54 mm. For some intervasculargamma radiation treatments, such as treatments on peripheral vessels ofthe cardiovascular system, the balloon treatment area length 30 may bein a range of approximately 10 mm to 250 mm.

Referring now to FIG. 3, during vascular radiotherapy, when inflated andengaged with the walls of the body vessel 16, the balloon outer lumens11 define a series of straight longitudinal paths 14 that allow forperfusion of blood (not shown) past balloon treatment area 30 (shown inFIG. 1).

The fluted balloon outer lumens 11 can be extruded with either equaldiameter 15 (as shown in FIGS. 3, 11 and 18) or with unequal (orasymmetrical) diameter 15 (as shown in FIG. 14). A balloon 10 havingouter lumens 11 with equal diameter 15 is well suited for a “standardRapid Exchange” catheter (shown in FIGS. 3 and 6) or an “over-the-wire”catheter type, each having a guidewire lumen 21 (and/or a guidewire 45)extending through one of the balloon's outer lumens. A balloon 10 havingouter lumens 11 with equal diameter 15 is also well suited for a “tipRapid Exchange” catheter type having only the source wire lumenextending through a treatment channel 50 contained within the ballooncentral lumen 12 (shown in FIG. 11).

Referring to FIG. 14, fluted outer lumens 11 with unequal diameter 15would provide the offset necessary to compensate for the slighteccentricity in the location of a treatment channel 50 (with theradiation source wire lumen 22 in it) within the central lumen 12 of theballoon 10. A balloon arrangement having outer lumens 11 with unequaldiameters (for example, a balloon assembly with one small “flute” andtwo large “flutes”) is best suited for the “standard RX” or“over-the-wire” catheter designs where the catheter shaft (or innermember) 41 includes two parallel lumens: a source lumen 22 (for aradiation source 25) and a guidewire lumen 21 (for a guidewire 45). Forvery small diameter centering balloon catheters, such as the 2 mmdiameter balloon catheter designs, the small “flute” 11 shown in FIG. 14may be eliminated to provide for centering of the radiation source lumen22.

The multi-lumen balloon 10 is manufactured using balloon materials, suchas Pebax™, nylon, polyethylene, polyurethane, or polyester. Materialsfor use in fabricating the multi-lumen balloon 1 0 of the presentinvention are selected by considering the properties and characteristics(e.g., softness, durability, low stiffness) required by angioplastyballoons, as well as considering properties necessary for successfulballoon fabrication (e.g., balloon material compatible with othercatheter materials and bonding process, material extruding well, etc.).When deployed (i.e., inflated), the multi-lumen balloon 10 is a highstrength, flexible, reasonably noncompliant balloon. The fluted shape ofthe balloon outer lumens allows the balloon to have improved bloodperfusion capability as well as improved balloon refoldingcharacteristics (where the inflation medium is removed from the balloonouter lumens).

Fluted Balloon Radiation Centering Catheter Assembly

With reference to FIGS. 1-16, four types of fluted balloon radiationcentering catheter assemblies are illustrated. In FIGS. 1-5, a flutedballoon radiation centering catheter assembly 1 for a “standard RapidExchange” catheter with a guidewire lumen 21 extending through one ofthe outer lumens is shown. In FIGS. 5-9, a fluted balloon radiationcentering catheter assembly 1 for a standard Rapid Exchange catheter 2with proximal and distal slideable seals is shown. In FIGS. 10-12, afluted balloon radiation centering catheter assembly 1 for a “tip (ordistal) Rapid Exchange” catheter 2 is illustrated. Finally, in FIGS.13-16, a fluted balloon radiation centering catheter assembly 1 for astandard Rapid Exchange catheter 2 with a guidewire lumen 21 extendingthrough the central lumen 12 is shown.

Multi-lumen Balloon Catheter Having a Guidewire Lumen Through BalloonOuter Lumen

Referring to FIG. 1, a multi-lumen fluted balloon radiation centeringcatheter assembly 1 with the balloon 10 in an inflated state is shown.The fluted balloon radiation centering catheter assembly 1 includes amulti-lumen balloon 10 and an interventional catheter 2. Interventionalcatheter 2 has a shaft 41 disposed proximate the balloon 10. The balloon10 includes a plurality of inflatable outer lumens 11 disposed around acentral lumen 12, the plurality of outer lumens 11 integrally coupledwith the central lumen 12 so as to form the multi-lumen balloon 10. Theballoon 10 has a distal seal 28 and a proximal seal 29. Distal seal 28seals the plurality of distal ends 34 b of the balloon outer lumens 11to the catheter shaft 41 while the proximal seal 29 seals the, pluralityof proximal ends 34 a of the balloon outer lumens 11 to the cathetershaft 41. Each of the outer lumens 11 takes the form of a “flute” (i.e.,an elongated cylinder having tapered ends) when inflated by an inflationmedium 18 b (shown in FIG. 3 for this balloon catheter assembly). Afluted balloon configuration is shown in FIG. 17, which is arepresentative illustration of balloon configurations of this invention(as revealed in balloon catheter assemblies of FIGS. 1, 6, 10, and 13).

Referring now to FIG. 3, the multi-lumen balloon catheter assembly 1 hasa radiation source lumen 22 that extends longitudinally through thecentral lumen 12 of the four-lumen balloon 10. In one embodiment, for a“standard Rapid Exchange” (standard RX) or an “over-the-wire” (OTW)catheter type, a guidewire lumen 21 (capable of containing a guidewire45) extends through one of the balloon outer lumens (as shown in FIG.3). The guidewire 45 allows positioning the multi-lumen centeringcatheter 1 (including its radiation source lumen 22) on the stenosedbody vessel area 16 for patient treatment.

The balloon radiation centering catheter assembly shown in FIG. 3 mayalso be used with a “tip (or distal) Rapid Exchange” catheter type, witha guidewire lumen 21 is distally positioned to the multi-lumen balloon10 and thus would not pass through the balloon 10.

For a “Standard RX” catheter type, the guidewire exists the cathetershaft at a distance in a range of approximately 15-35 cm from the distaltip of the catheter. For a “tip RX” catheter type, the guidewire existsthe catheter shaft at a distance in a range of approximately 3-20 mmfrom the distal tip of the catheter. Note that for a tip RX cathetertype, the guidewire does not enter the balloon. For the “OTW” cathetertype, the guidewire extends through the catheter shaft. The distancefrom the distal tip of the catheter to the inflation port may be in arange of approximately 75-135 cm for coronary applications and in arange of approximately 75-145 cm for peripheral applications. For anycatheter type, if an afterloader (i.e., radiation therapy device) is tobe used, the guidewire may be extended an additional 15-125 cm. In oneembodiment, when using the afterloader the guidewire extension may be ina range of approximately 70-80 cm.

Continuing with reference to FIG. 3, as mentioned above, the radiationsource lumen 22 extends longitudinally through the balloon central lumenand the standard RX guidewire lumen 21 extends longitudinally throughone of the balloon outer lumens 11. The remaining two outer lumens 11are then sealed onto the radiation source lumen 22 and the guidewirelumen 21 for maintaining inflation pressure in the balloon. Wheninflated by an inflation medium 18 b, the balloon outer lumens 11 formflutes positioned parallel to the radiation source lumen 22 and theguidewire lumen 21. During vascular radiotherapy, when inflated andengaged with the walls of the body vessel 16, the balloon outer lumens11 define a series of straight longitudinal paths 14 that allow forperfusion of blood (not shown) past balloon treatment area 30 (shown inFIG. 1).

The fluted balloon outer lumens 11 can be extruded with either equaldiameter 15 (as shown in FIGS. 3, 11 and 18) or with unequal (orasymmetrical) diameter 15 (as shown in FIG. 14). A balloon 10 havingouter lumens 11 with equal diameter 15 is well suited for a “standardRapid Exchange” catheter (shown in FIGS. 3 and 6) or an “over-the-wire”catheter type, each having a guidewire lumen 21 (and/or a guidewire 45)extending through one of the balloon's outer lumens. A balloon 10 havingouter lumens 11 with equal diameter 15 is also well suited for a “tipRapid Exchange” catheter type having only the source wire lumenextending through a treatment channel 50 contained within the ballooncentral lumen 12 (shown in FIG. 11).

Continuing with reference to FIG. 3, the diameter 18 a of the ballooncentral lumen 12 is sized based on the radiation source outer diameter,for example a radiation source wire having an outer diameter in a rangeof approximately {fraction (10/1000)} in. to {fraction (50/1000)} in.The combined balloon diameter 13 (as measured across all balloon outerlumens 11 while balloon, is in an inflated or deployed state) is kept ina range of approximately 1.5 mm to 6 mm for coronary vessels and in arange of approximately 3 mm to 12 mm for peripheral vessels. For theembodiment shown in FIG. 3, a balloon having a combined diameter 13 in arange of approximately 1.5 mm to 4 mm is advantageous when treatingcoronary vessels.

Referring to FIG. 4 (which represents a cross-sectional view of themulti-lumen fluted balloon radiation centering catheter assembly of FIG.1 taken along line C—C), the catheter shaft 41 includes an inner lumen41 a that extends longitudinally through at least a portion of thecatheter shaft 41 proximate the balloon 10 and connects to the centrallumen 12 of the balloon 10. The catheter shaft inner lumen 41 a isadapted for receiving a radiation source lumen 22 with a radiationsource 25 and a guidewire lumen 21 capable of containing a guidewire 45for positioning the multi-lumen balloon radiation centering catheter 1within a body vessel. Both the radiation source lumen 22 and theguidewire lumen 21 are manufactured as co-extrusions having an innerlayer made of a material such as polyethylene and an outer layer made ofa material such as Pebax, nylon, or Primacor.

Continuing with reference to FIG. 4, the catheter shaft inner lumen 41 ais further adapted to receive at least one inflation lumen (54 b, 55 b)that is in fluid communication with each of the balloon outer lumens toallow an inflation fluid to enter and inflate the outer lumens 11 andthus, center the radiation source lumen 22 within a body vessel 16. Theinflation lumen(s) (54 b, 55 b) in the catheter shaft inner lumen 41 aare generally formed when the multi-lumen balloon 10 is bonded to thecatheter shaft 41 during the catheter proximal seal 29 construction(explained in more detail in the Proximal Seal section).

As mentioned above, having individual inflation lumens for each of theballoon outer lumens allows each balloon outer lumen to be inflated todifferent pressures. However, it is not necessary to have individualinflation lumens for each of the balloon outer lumens in order to centerto radiation source lumen with the vessel. For balloon catheter designswhere individual inflation lumens (54 b, 55 b) are absent, the cathetershaft inner lumen 41 a may serve as an inflation lumen for the balloonouter lumens 11.

Referring to FIG. 5 (which represents a cross-sectional view of themulti-lumen fluted balloon radiation centering catheter assembly of FIG.1 taken along line D—D), at the region of the balloon catheter proximalseal 29, an elongated flexible catheter outer member 46 is placed overthe catheter shaft 41. The catheter outer member may be manufactured ofmaterials such as nylon, Pebax, polyurethane, etc. Catheter outer member46 includes a lumen 50 a that extends longitudinally therein. Near thecatheter proximal seal 29 region, the lumen 50 a becomes the cathetershaft inner lumen 41 a. Lumen 50 a is adapted for receiving a commoninflation lumen 36 for inflating and pressurizing the balloon outerlumens 11 with an inflation medium (or means) 18 b. The inflation medium18 b could include any inflation medium known in the art of balloonangioplasty, such as air, saline solution, or contrast fluid.

Continuing with reference to FIG. 5, the catheter outer member innerlumen 50 a is adapted for receiving a radiation source lumen 22 with aradiation source 25. If a Standard RX (Rapid Exchange) or an OTWinterventional catheter assembly 2 is used, the catheter outer memberlumen 50 a is further adapted for receiving a guidewire lumen 21 (and/ora guidewire 45).

Referring now to FIG. 1, the multi-lumen balloon has a treatment area 30is defined between the balloon's distal seal 28 and proximal seal 29.The longitudinal length of the balloon treatment area 30 is made to beappropriate for the body vessel to be treated (for example, coronaryvessels or peripheral vessels) and for the radiation treatment to bedelivered. In one embodiment of the present invention, the balloontreatment area length 30 is in a range of approximately 18 mm to 54 mm.For some intervascular gamma radiation treatments, such as treatments onperipheral vessels of the cardiovascular system, the balloon treatmentarea length 30 may be in a range of approximately 10 mm to 250 mm.

Continuing with reference to FIG. 1, in one embodiment, the radiationsource lumen 22 is sealed at its distal end 23 with plug 24 to allow aradiation source 25 to be placed inside the radiation source lumen 22.In another embodiment, the radiation source lumen 22 is left open at itsdistal end 23 (i.e., it does not have a plug 24) so that a radiationsource 25 (placed inside the radiation source lumen 22) can be distallyadvanced past the multi-lumen balloon 10. Furthermore, not having theradiation source lumen 22 sealed with the plug 24 decreases thestiffness of the multi-lumen balloon even further.

It should be noted that it is not necessary to have a radiation sourcelumen 22 as part of the multi-lumen balloon centering catheter assembly1. In some applications, it may be desirable to place the radiationsource 25 directly within the central lumen 12 of the balloon 10,without employing a source lumen 22. Not having a radiation source lumen22 in the balloon central lumen 12 reduces the size of the multi-lumenballoon and decreases the stiffness of the multi-lumen balloon (sincethe radiation source lumen 22 is a co-extruded shaft), thus allowing theballoon to cross tortuous paths more easily along the body vessel.

The radiation source 25, which may be shaped in the form of a wire,seed, pellets, ribbon, etc., is positioned inside radiation source lumen22 and is then advanced longitudinally along a prescribed vessel length16 during patient treatment. In one embodiment of this invention, themulti-lumen balloon centering catheter assembly 1 uses a Phosphorus-32radiation source as a radiation source 24. However, the multi-lumenballoon of this invention can be used with any radiation source employedin vascular radiotherapy, which includes gamma radiation emittingsources and beta radiation emitting sources known in the art.

Continuing with reference to FIG. 1, two radio-opaque markers, a distalmarker 37 and a proximal marker 38, may be attached to the radiationsource lumen 22. The radio-opaque markers 37 and 38 are used forpositioning the interventional catheter 1 under fluoroscopy, as well asfor assisting the stepping (via manual or automatic means) of theradiation source 25 over the entire prescribed region of the vessel 16to be treated. The markers 37 and 38 are made of any materials known inthe art of radio-opaque markers, such as silver, gold, platinum,tungsten, that allow markers to become visible under fluoroscopy. In oneembodiment, the radio-opaque markers (37, 38) are attached within thelimits of the balloon's treatment area 30. In one configuration, thedistal marker 37 is incorporated into the plug 24 of the source lumen22. In another configuration, radio-opaque markers (37, 38) may be partof a separate device (not shown) that is independent of the ballooncatheter assembly.

A soft tip 26 is attached to the distal end 27 of the guidewire lumen 21to improve trackability and reduce trauma to the body vessel. The lengthof the soft tip 26 depends on the type of catheter design used, however,the length of the tip is generally in a range of approximately 0.5 mm to10 mm.

With reference to FIG. 1, the balloon 10 is attached to catheter shaft41 of the catheter assembly 2. The ballodn's proximal seal 29 isattached at a proximal end 44 of flexible catheter shaft 41, near theinflation/deflation port 33. The balloon distal seal 28 is attached tothe catheter shaft 41 adjacent to the location where the radiationsource lumen 22 ends. In one embodiment, the balloon 10 and assembly 2are attached by using a laser bond technique. Bonds may also be doneusing other balloon bonding techniques known in the art, such as thermalor ultrasonic welds, adhesive welds, or other conventional means. Thedistal and proximal seals (28, 29) may each have a width in a range ofapproximately 0.5 mm to about 5 mm.

Multi-lumen Balloon Catheter Having a Slideable Proximal Seal and aSlideable Distal Seal

Referring to FIGS. 6-9, a fluted balloon radiation centering catheterassembly for a standard Rapid Exchange catheter with proximal and distalslideable seals is shown. In the embodiment disclosed herein, the tubingused to form the guidewire lumen is eliminated, and is replaced byproximal slideable seal 29 a and distal slideable seal 28 a as shown inFIG. 6. Eliminating the guidewire tubing reduces the material used andlowers the balloon catheter proximal seal outer diameter. Theseimprovements make the catheter less stiff, allowing the balloon catheterto cross tortuous paths more easily along the body vessel. Furthermore,eliminating the guidewire tubing allows the proximal seal to become lesscomplicated during seal manufacturing (as discussed in more detail in alater section).

With reference to FIG. 6, the path of the rapid exchange guidewire 45starts at the distal tip 26 of the catheter 1 by entering an annularspace 45 b (shown in FIG. 7) formed between the catheter shaft 41 andthe distal end of the radiation source lumen 22. This is where theslideable distal seal 28 a is located. The guidewire 45 thenlongitudinally passes through one of the balloon outer lumens 11, wherethe balloon outer lumen 11 itself acts as a guidewire lumen. Theguidewire 45 then runs in the annular space 52 (shown in FIG. 8) betweenthe shaft outer member 46 and the source lumen 22 until it reaches anexit notch 29b with a slideable proximal seal 29 a. These annular spaces45 b and 52 are also used to inflate and deflate the multi-lumenballoon, so “slideable” seals are used at both the catheter tip 26 andat the guidewire exit notch 29 b.

Referring to FIG. 7, as stated above, the guidewire 45 enters an annularspace 45 b (shown in FIG. 7) formed between the catheter shaft 41 andthe distal end of the radiation source lumen 22. To create the slideabledistal seal 28 a, the annular space 45 b is made to be a “close fit” byhaving a minimal distance clearance between the outer diameter of theguidewire 45 and the inner diameter of the balloon seal (formed when theballoon is being bonded to the catheter shaft).

Referring to FIG. 8, after exiting the balloon outer lumen, theguidewire 45 then enters an annular space 52 (shown in FIG. 8) formed inthe catheter shaft outer member 46. The annular space (or lumen) 52serves both as a lumen for the guidewire 45 and as an inflation lumenfor the balloon outer lumen that has the guidewire contained therein.

The slideable distal and proximal seals (28 a, 29 a) prevent the ballooninflation media (for example, saline) (not shown) from leaking out ofthe catheter 2. However, the slideable seals (28 a, 29 a) to theguidewire 45 are not fixed, rather the design allows the guidewire toslide axially relative to the catheter 2 and also allows the guidewire45 to be rotated relative to the catheter. In one embodiment, thecombination of a sealing capability with relative motion is obtained byhaving minimal clearances between the outer diameter of the guidewire 45and the inner diameter 45 aa of the seal formed between the balloon andthe catheter shaft (as shown in FIG. 7).

Another embodiment of the slideable proximal and distal seals uses ahydrogel material 45 a (shown in FIG. 7), positioned either on theguidewire 45 or integral to the slideable distal and proximal seals (28a, 29 a) to maintain the pressure seal while providing smoother movementof the guidewire 45. To insure that the seals (28 a, 29 a) holdpressure, the catheter 2 may be used with guidewires that have a polymerjacket rather than an intermediate wire coil. In a yet anotherembodiment, the hydrogel material in the slideable proximal and distalseals is substituted with an O-ring 45 a (shown in FIG. 9). This O-ringis positioned either on the guidewire 45 or integral to the slideabledistal and proximal seals (28 a, 29 a) to maintain the pressure sealwhile providing smoother movement of the guidewire 45.

Referring to FIG. 6, a multi-lumen fluted balloon radiation centeringcatheter assembly 1 with the balloon 10 in an inflated state is shown.The fluted balloon radiation centering catheter assembly 1 includes amulti-lumen balloon 10 and an interventional catheter 2. Interventionalcatheter 2 has a shaft 41 disposed proximate to the balloon 10. Theballoon 10 includes a plurality of inflatable outer lumens 11 disposedaround a central lumen 12, the plurality of outer lumens 11 integrallycoupled with the central lumen 12 so as to form the multi-lumen balloon10. The balloon 10 has a slideable distal seal 28 a and a slideableproximal seal 29 a. Slideable distal seal 28 a seals the plurality ofdistal ends 34 b of the balloon outer lumens 11 to the catheter shaft 41while the slideable proximal seal 29 a seals the plurality of proximalends 34 a of the balloon outer lumens 11 to the catheter shaft 41.

Each of the outer lumens 11 takes the form of a “flute” (i.e., anelongated cylinder having tapered ends) when inflated by an inflationmedium. A fluted balloon configuration is shown in FIG. 17, which is arepresentative illustration of balloon configurations of this invention.During vascular radiotherapy, when inflated and engaged with the wallsof the body vessel 16, the balloon outer lumens 11 define a series ofstraight longitudinal paths that allow for perfusion of blood past aballoon treatment area 30 (shown in FIG. 6). The longitudinal length ofthe balloon treatment area 30 is made to be appropriate for the bodyvessel to be treated (for example, coronary vessels or peripheralvessels) and for the radiation treatment to be delivered. In oneembodiment of the present invention, the balloon treatment area length30 is in a range of approximately 18 mm to 54 mm. For some intervasculargamma radiation treatments, such as treatments on peripheral vessels ofthe cardiovascular system, the balloon treatment area length 30 may bein a range of approximately 10 mm to 250 mm.

The fluted balloon outer lumens 11 can be extruded with either equaldiameter 15 (as shown in FIGS. 3, 11 and 18) or with unequal (orasymmetrical) diameter 15 (as shown in FIG. 14).

Continuing with reference to FIG. 6, the balloon central lumen 12 issized based on the radiation source outer diameter, for example aradiation source wire having an outer diameter in a range ofapproximately {fraction (10/1000)} in. to {fraction (50/1000)} in. Thecombined balloon diameter 13 (as measured across all balloon outerlumens 11 while balloon is in an inflated or deployed state) is kept ina range of approximately 1.5 mm to 6 mm for coronary vessels and in arange of approximately 3 mm to 12 mm for peripheral vessels. For theembodiment shown in FIG. 6, a balloon having a combined diameter 13 in arange of approximately 1.5 mm to 4 mm is advantageous when treatingcoronary vessels.

Continuing with reference to FIG. 6, the multi-lumen balloon catheterassembly 1 has a radiation source lumen 22 that extends longitudinallythrough the central lumen 12 of the four-lumen balloon 10. In thisembodiment, a guidewire 45 without a guidewire lumen tubing extendsthrough one of the balloon outer lumens (as shown in FIG. 6). Theguidewire 45 allows positioning the multi-lumen centering catheter 1(including its radiation source lumen 22) on the stenosed body vesselarea for patient treatment.

Continuing with reference to FIG. 6, in one embodiment, the radiationsource lumen 22 is sealed at its distal end with plug 24 to allow aradiation source 25 to be placed inside the radiation source lumen 22.In another embodiment, the radiation source lumen 22 is left open at itsdistal end 23 (i.e., it does not have a plug 24) so that a radiationsource 25 (placed inside the radiation source lumen 22) can be distallyadvanced past the multi-lumen balloon 10. Furthermore, not having theradiation source lumen 22 sealed with the plug 24 decreases thestiffness of the multi-lumen balloon even further.

It should be noted that it is not necessary to have a radiation sourcelumen 22 as part of the multi-lumen balloon centering catheter assembly1. In some applications, it may be desirable to place the radiationsource 25 directly within the central lumen 12 of the balloon 10,without employing a source lumen 22. Not having a radiation source lumen22 in the balloon central lumen 12 reduces the size of the multi-lumenballoon and decreases the stiffness of the multi-lumen balloon (sincethe radiation source lumen,22 is a co-extruded shaft), thus allowing theballoon to cross tortuous paths more easily along the body vessel.

The radiation source 25, which may be shaped in the form of a wire,seed, pellets, ribbon, etc., is positioned inside radiation source lumen22 and is then advanced longitudinally along a prescribed vessel length16 during patient treatment. In one embodiment of this invention, themulti-lumen balloon centering catheter assembly 1 uses a Phosphorus-32radiation source as a radiation source 24. However, the multi-lumenballoon of this invention can be used with any radiation source employedin vascular radiotherapy, which includes gamma radiation emittingsources and beta radiation emitting sources known in the art.

Continuing with reference to FIG. 6, two radio-opaque markers, a distalmarker 37 and a proximal marker 38, may be attached to the radiationsource lumen 22. The radio-opaque markers 37 and 38 are used forpositioning the interventional catheter 1 under fluoroscopy, as well asfor assisting the stepping (via manual or automatic means) of theradiation source 25 over the entire prescribed region of the vessel 16to be treated. The markers 37 and 38 are made of any materials known inthe art of radio-opaque markers, such as silver, gold, platinum,tungsten, that allow markers to become visible under fluoroscopy. In oneembodiment, the radio-opaque markers (37, 38) are attached within thelimits of the balloon's treatment area 30. In one configuration, thedistal marker 37 is incorporated into the plug 24 of the source lumen22. In another configuration, radio-opaque markers (37, 38) may be partof a separate device (not shown) that is independent of the ballooncatheter assembly.

A soft tip 26 (shown in FIG. 6) is attached to the distal end 27 of theguidewire 45 to improve trackability and reduce trauma to the bodyvessel. The length of the soft tip 26 depends on the type of catheterdesign used, however, the length of the tip is generally in a range ofapproximately 0.5 mm to 10 mm.

Referring now to FIG. 8 (which represents a cross-sectional view of themulti-lumen fluted balloon radiation centering catheter assembly of FIG.6 taken along line F—F), the catheter shaft 41 includes an inner lumen41 a that extends longitudinally through at least a portion of thecatheter shaft 41 proximate the balloon 10 and connects to the centrallumen 12 of the balloon 10. The catheter shaft inner lumen 41 a isadapted for receiving a radiation source lumen 22 with a radiationsource 25. The radiation source lumen 22 is manufactured as aco-extruded shaft having an inner layer made of a material such aspolyethylene and an outer layer made of a material such as Pebax, nylon,or Primacor.

Continuing with reference to FIG. 8, the catheter shaft inner lumen 41 ais further adapted to receive a plurality of inflation lumens (51, 52)that are in fluid communication with each of the balloon outer lumens toallow an inflation fluid to enter and inflate the outer lumens 11 andthus, center the radiation source lumen 22 within a body vessel 16. Notethat lumen 52 serves as both an inflation lumen and as a guidewirelumen. The inflation lumens (51, 52) in the catheter shaft inner lumen41 a are generally formed when the multi-lumen balloon 10 is bonded tothe catheter shaft 41 during the catheter slideable proximal seal 29 aconstruction. As mentioned above, having individual inflation lumens foreach of the balloon outer lumens allows each balloon outer lumen to beinflated to different pressures.

Referring to FIG. 9 (which represents a cross-sectional view of themulti-lumen fluted balloon radiation centering catheter assembly of FIG.6 taken along line G—G), at the region of the balloon catheter slideableproximal seal 29 a, an elongated flexible catheter outer member 46 isplaced over the catheter shaft 41. Catheter outer member 46 includes alumen 50 a that extends longitudinally therein. Past the catheterslideable proximal seal 29 a region, the lumen 50 a becomes the cathetershaft inner lumen 41 a.

Lumen 50 a is adapted for receiving a common inflation lumen 36 forinflating and pressurizing the balloon outer lumens 11 with an inflationmedium (or means) 18 b. The inflation medium 18 b could include anyinflation medium known in the art of balloon angioplasty, such as air,saline solution, or contrast fluid. The catheter outer member innerlumen 50 a is further adapted for receiving a radiation source lumen 22(with a radiation source) and a guidewire lumen 21. At the slideableproximal seal 29 a, to ensure a tight and close fit, the guidewire lumen21 in the catheter outer member 46 is adapted for receiving a hydrogelmaterial or an O-ring 45 a. The catheter outer member 46 may bemanufactured of materials such as nylon, Pebax, polyurethane, etc.

Multi-lumen Balloon Catheter Having a Balloon with Communication Boresbetween Central and Outer Lumens and a Tip Rapid Exchange GuidewireLumen

With reference to FIGS. 10-16, two embodiments of a multi-lumen flutedballoon radiation centering catheter assembly are shown. Both catheterassemblies include a multi-lumen balloon having communication boresbetween the central lumen and the outer lumens. In FIGS. 10-12, a flutedballoon radiation centering catheter assembly for a “tip (or distal)Rapid Exchange” catheter 2 is illustrated, while in FIGS. 13-16, afluted balloon radiation centering catheter assembly 1 for a standardRapid Exchange catheter with a guidewire lumen extending through thecentral lumen is shown.

Referring to FIG. 10, a multi-lumen fluted balloon radiation centeringcatheter assembly 1 with the balloon 10 in an inflated state is shown.The fluted balloon radiation centering catheter assembly 1 includes amulti-lumen balloon 10 and an interventional catheter 2. Interventionalcatheter 2 has a shaft disposed proximate the balloon 10. The balloon 10includes a plurality of inflatable outer lumens 11 disposed around acentral lumen 12, the plurality of outer lumens 11 integrally coupledwith the central lumen 12 so as to form the multi-lumen balloon 10. Theballoon 10 has a distal seal 28 and a proximal seal 29. Distal seal 28seals the plurality of distal ends 34 b of the balloon outer lumens 11to the catheter shaft 41 while the proximal seal 29 seals the pluralityof proximal ends 34 a of the balloon outer lumens 11 to the cathetershaft 41. The distal and proximal seals (28, 29) may each have a widthin a range of approximately 0.5 mm to about 5 mm.

Each of the outer lumens 11 takes the form of a “flute” (i.e., anelongated cylinder having tapered ends) when inflated by an inflationmedium 18 b (shown in FIG. 11 for this balloon catheter assembly). Afluted balloon configuration is shown in FIG. 17, which is arepresentative illustration of balloon configurations of this invention(as revealed in balloon catheter assemblies of FIGS. 1, 6, 10, and 13).

Continuing with reference to: FIG. 10, the catheter shaft includes aninner tubular member 41 having a distal treatment section 42 with adistal end 43 and a proximal end 44, and a proximate section (notshown). The inner tubular member 41 has an inner lumen 41 a. Thecatheter shaft further includes a flexible elongate outer tubular member46 having a distal section 47 with a distal end 48, and a proximatesection (not shown). Elongate inner tubular member 41 extends coaxiallywithin the elongate outer tubular member 46.

Referring now to FIG. 11, the balloon central lumen 12 is capable ofcontaining a radiation source 25 (with or without a radiation sourcelumen 22) therein. The multi-lumen balloon embodiment shown in FIG. 11is adapted for receiving a guidewire lumen (with a guidewire) throughits central lumen 12 (as shown in FIG. 14). Because in FIG. 11 theballoon 10 is shown as being used with a tip (or distal) Rapid Exchangecatheter type (i.e., the guidewire is positioned distal to the balloon),for the balloon embodiment of FIG. 11, the guidewire does not extendthrough any of the balloon lumens 11.

For the balloon configuration shown in FIG. 11, the balloon 10 includesbores (or channels) 35 that are formed between the outer lumens 11 andthe central lumen 12. This arrangement allows an inflation medium 18 bto pass from the balloon central lumen 12 into the outer lumens 11 andinflate outer lumens 11, causing a radiation source lumen 22 to becentered within a body vessel 16. In this configuration, the centrallumen 12 is pressurized in order for the outer lumens 11 to properlyinflate and center the radiation source lumen 22 within the body vessel16. The catheter inner lumen 41 a is adapted to serve as an inflationlumen for the balloon central lumen 12 and the outer lumens 11.

Continuing with reference to FIG. 11, as mentioned above, the radiationsource lumen 22 extends longitudinally through the balloon centrallumen. When using a tip RX radiation catheter type, the plurality ofouter lumens 11 are sealed onto the radiation source lumen 22 formaintaining inflation pressure in the balloon. When inflated by aninflation medium 18 b, the balloon outer lumens 11 form flutespositioned parallel to the radiation source lumen 22. During vascularradiotherapy, when inflated and engaged with the walls of the bodyvessel 16, the balloon outer lumens 11 define a series of straightlongitudinal paths 14 that allow for perfusion of blood (not shown) pastballoon treatment area 30 (shown in FIG. 10).

The fluted balloon outer lumens 11 can be extruded with either equaldiameter 15 (as shown in FIG. 11) or with unequal (or asymmetrical)diameter 15 (as shown in FIG. 14). A balloon 10 having outer lumens 11with equal diameter 15 is well suited for a “tip Rapid Exchange”catheter type having only the source wire lumen extending through atreatment channel 50 contained within the balloon central lumen 12(shown in FIG. 11).

Continuing with reference to FIG. 11, the diameter 18 a of the ballooncentral lumen 12 is sized based on the radiation source outer diameter,for example a radiation source wire having an outer diameter in a rangeof approximately {fraction (10/1000)} in. to {fraction (50/1000)} in.The combined balloon diameter 13 (as measured across all balloon outerlumens 11 while balloon is in an inflated or deployed state) is kept ina range of approximately 1.5 mm to 6 mm for coronary vessels and in arange of approximately 3 mm to 12 mm for peripheral vessels. For theembodiment shown in FIG. 11, a balloon having a combined diameter 13 ina range of approximately 1.5 mm to 4 mm is advantageous when treatingcoronary vessels.

Referring now to FIG. 10, the multi-lumen balloon has a treatment area30 is defined between the balloon's distal seal 28 and proximal seal 29.The longitudinal length of the balloon treatment area 30 is made to beappropriate for the body vessel to be treated (for example, coronaryvessels or peripheral vessels) and for the radiation treatment to bedelivered. In one embodiment of the present invention, the balloontreatment area length 30 is in a range of approximately 18 mm to 54 mm.For some intervascular gamma radiation treatments, such as treatments onperipheral vessels of the cardiovascular system, the balloon treatmentarea length 30 may be in a range of approximately 10 mm to 250 mm.

Continuing with reference to FIG. 10, in one embodiment, the radiationsource lumen 22 is sealed at its distal end 23 with plug 24 to allow aradiation source 25 to be placed inside the radiation source lumen 22.In another embodiment, the radiation source lumen 22 is left open at itsdistal end 23 (i.e., it does not have a plug 24) so that a radiationsource 25 (placed inside the radiation source lumen 22) can be distallyadvanced past the multi-lumen balloon 10. Furthermore, not having theradiation source lumen 22 sealed with the plug 24 decreases thestiffness of the multi-lumen balloon even further.

It should be noted that it is not necessary to have a radiation sourcelumen 22 as part of the multi-lumen balloon centering catheter assembly1. In some applications, it may be desirable to place the radiationsource 25 directly within the central lumen 12 of the balloon 10,without employing a source lumen 22. Not having a radiation source lumen22 in the balloon central lumen 12 reduces the size of the multi-lumenballoon and decreases the stiffness of the multi-lumen balloon (sincethe radiation source lumen 22 is a co-extruded shaft), thus allowing theballoon to cross tortuous paths more easily along the body vessel.

The radiation source 25, which may be shaped in the form of a wire,seed, pellets, ribbon, etc., is positioned inside radiation source lumen22 and is then advanced longitudinally along a prescribed vessel length16 during patient treatment. In one embodiment of this invention, themulti-lumen balloon centering catheter assembly 1 uses a Phosphorus-32radiation source as a radiation source 24. However, the multi-lumenballoon of this invention can be used with any radiation source employedin vascular radiotherapy, which includes gamma radiation emittingsources and beta radiation emitting sources known in the art.

Continuing with reference to FIG. 10, two radio-opaque markers, a distalmarker 37 and a proximal marker 38, may be attached to the radiationsource lumen 22. The radio-opaque markers 37 and 38 are used forpositioning the interventional catheter 1 under fluoroscopy, as well asfor assisting the stepping (via manual or automatic means) of theradiation source 25 over the entire prescribed region of the vessel 16to be treated. The markers 37 and 38 are made of any materials known inthe art of radio-opaque markers, such as silver, gold, platinum,tungsten, that allow markers to become visible under fluoroscopy. In oneembodiment, the radio-opaque markers (37, 38) are attached within thelimits of the balloon's treatment area 30. In one configuration, thedistal marker 37 is incorporated into the plug 24 of the source lumen22. In another configuration, radio-opaque markers (37, 38) may be partof a separate device (not shown) that is independent of the ballooncatheter assembly.

A soft tip 26 is attached to the distal end 27 of the guidewire lumen 21to improve trackability and reduce trauma to the body vessel. The lengthof the soft tip 26 depends on the type of catheter design used, however,the length of the tip is generally in a range of approximately 0.5 mm to10 mm.

With reference to FIG. 10, the balloon 10 is attached to catheter shaft41 of the catheter assembly 2. The balloon's proximal seal 29 isattached at a proximal end 44 of flexible catheter shaft 41, near theinflation/deflation port 33. The balloon distal seal 28 is attached tothe catheter shaft 41 adjacent to the location where the radiationsource lumen 22 ends. In one embodiment, the balloon 10 and assembly 2are attached by using a laser bond technique. Bonds may also be doneusing other balloon bonding techniques known in the art, such as thermalor ultrasonic welds, adhesive welds, or other conventional means.

Multi-lumen Balloon Catheter Having a Balloon with Communication Boresbetween Central and Outer Lumens and a Guidewire Lumen Through theCentral Lumen

In FIGS. 13-16, a fluted balloon radiation centering catheter assembly 1for a standard Rapid Exchange catheter with a guidewire lumen extendingthrough the central lumen of a multi-lumen balloon is shown.

Referring to FIG. 13, a multi-lumen fluted balloon radiation centeringcatheter assembly 1 with the balloon 10 in an inflated state is shown.The fluted balloon radiation centering catheter assembly 1 includes amulti-lumen balloon 10 and an interventional catheter 2. Interventionalcatheter 2 has a shaft disposed proximate the balloon 10. The balloon 10includes a plurality of inflatable outer lumens 11 disposed around acentral lumen 12, the plurality of outer lumens 11 integrally coupledwith the central lumen 12 so as to form the multi-lumen balloon 10. Theballoon 10 has a distal seal 28 and a proximal seal 29. Distal seal 28seals the plurality of distal ends 34 b of the balloon outer lumens 11to the catheter shaft 41 while the proximal seal 29 seals the pluralityof proximal ends 34 a of the balloon outer lumens 11 to the cathetershaft 41. The distal and proximal seals (28, 29) may each have a widthin a range of approximately 0.5 mm to about 5 mm.

Each of the outer lumens 11 takes the form of a “flute” (i.e., anelongated cylinder having tapered ends) when inflated by an inflationmedium 18 b (shown in FIG. 14 for this balloon catheter assembly). Afluted balloon configuration is shown in FIG. 17, which is arepresentative illustration of balloon configurations of this invention(as revealed in balloon catheter assemblies of FIGS. 1, 6, 10, and 13).

Continuing with reference to FIG. 13, the catheter shaft includes aninner tubular member 41 having an inner lumen 41 a. The catheter shaftfurther includes a flexible elongate outer tubular member 46. Elongateinner tubular member 41 extends coaxially within the elongate outertubular member 46.

Referring now to FIG. 14, the balloon central lumen 12 is capable ofcontaining a radiation source 25 (with or without a radiation sourcelumen 22) therein. The multi-lumen balloon embodiment shown in FIG. 14is further adapted for receiving a guidewire lumen (with a guidewire 45)through its central lumen 12.

For the balloon configuration shown in FIG. 14, the balloon 10 includesbores (or channels) 35 that are formed between the outer lumens 11 andthe central lumen 12. This arrangement allows an inflation medium 18 bto pass from the balloon central lumen 12 into the outer lumens 11 andinflate outer lumens 11, causing a radiation source lumen 22 to becentered within a body vessel 16. In this configuration the centrallumen 12 is pressurized in order for the outer lumens 11 to properlyinflate and center the radiation source lumen 22 within the body vessel16. The catheter inner lumen 41 a is adapted to serve as an inflationlumen for the balloon central lumen 12 and the outer lumens 11 (as shownin FIG. 16).

Continuing with reference to FIG. 14, when using a standard RX or anover-the-wire radiation catheter type, the radiation source lumen 22 andthe guidewire lumen 21 extend longitudinally through the balloon centrallumen. The plurality of outer lumens 11 are sealed onto the radiationsource lumen 22 and the guidewire lumen 21 for maintaining inflationpressure in the balloon. When inflated by an inflation medium 18 b, theballoon outer lumens 11 form flutes positioned parallel to the radiationsource lumen 22. During vascular radiotherapy, when inflated and engagedwith the walls of the body vessel 16, the balloon outer lumens 11 definea series of straight longitudinal paths 14 that allow for perfusion ofblood (not shown) past balloon treatment area 30 (shown in FIG. 13).

The fluted balloon outer lumens 11 can be extruded with either equaldiameter 15 (as shown in FIG. 11) or with unequal (or asymmetrical)diameter 15 (as shown in FIG. 14). A balloon arrangement having outerlumens 11 with unequal diameters (for example, a balloon assembly ofFIG. 14 with one small “flute” and two large “flutes”) is best suitedfor the “standard RX” or “over-the-wire” catheter designs where thecatheter shaft (or inner member) 41 includes two parallel lumens: asource lumen 22 (for a radiation. source 25) and a guidewire lumen 21(for a guidewire 45). For very small diameter centering ballooncatheters, such as the 2 mm diameter balloon catheter designs, the small“flute” 11 shown in FIG. 14 may be eliminated to provide for centeringof the radiation source lumen 22.

Continuing with reference to FIG. 14, the diameter 18 a of the ballooncentral lumen 12 is sized based on the radiation source outer diameterand the guidewire lumen outer diameter, for example a radiation sourcewire having an outer diameter in a range of approximately {fraction(10/1000)} in. to {fraction (50/1000)} in and a guidewire lumen havingan outer diameter in a range of approximately {fraction (10/1000)} in.to {fraction (15/1000)}. The combined balloon diameter 13 (as measuredacross all balloon outer lumens 11 while balloon is in an inflated ordeployed state) is kept in a range of approximately 1.5 mm to 6 mm forcoronary vessels and in a range of approximately 3 mm to 12 mm forperipheral vessels. For the embodiment shown in FIG. 14, a balloonhaving a combined diameter 13 in a range of approximately 1.5 mm to 4 mmis advantageous when treating coronary vessels.

Referring now to FIG. 13, the multi-lumen balloon has a treatment area30 is defined between the balloon's distal seal 28 and proximal seal 29.The longitudinal length of the balloon treatment area 30 is made to beappropriate for the body vessel to be treated (for example, coronaryvessels or peripheral vessels) and for the radiation treatment to bedelivered. In one embodiment of the present invention, the balloontreatment area length 30 is in a range of approximately 18 mm to 54 mm.For some intervascular gamma radiation treatments, such as treatments onperipheral vessels of the cardiovascular system, the balloon treatmentarea length 30 may be in a range of approximately 10 mm to 250 mm.

Continuing with reference to FIG. 13, in one embodiment, the radiationsource lumen 22 is sealed at its distal end 23 with plug 24 to allow aradiation source 25 to be placed inside the radiation source lumen 22.In another embodiment, the radiation source lumen 22 is left open at itsdistal end 23 (i.e., it does not have a plug 24) so that a radiationsource 25 (placed inside the radiation source lumen 22) can be distallyadvanced past the multi-lumen balloon 10. Furthermore, not having theradiation source lumen 22 sealed with the plug 24 decreases thestiffness of the multi-lumen balloon even further.

It should be noted that it is not necessary to have a radiation sourcelumen 22 as part of the multi-lumen balloon centering catheter assembly1. In some applications, it may be desirable to place the radiationsource 25 directly within the central lumen 12 of the balloon 10;without employing a source lumen 22. Not having a radiation source lumen22 in the balloon central lumen 12 reduces the size f the multi-lumenballoon and decreases the stiffness of the multi-lumen balloon since theradiation source lumen 22 is a co-extruded shaft), thus allowing theballoon to cross tortuous paths more easily along the body vessel.

The radiation source 25, which may be shaped in the form of a wire,seed, pellets, ribbon, etc., is positioned inside radiation source lumen22 and is then advanced longitudinally along a prescribed vessel length16 during patient treatment. In one embodiment of this invention, themulti-lumen balloon centering catheter assembly 1 uses a Phosphorus-32radiation source as a radiation source 24. However, the multi-lumenballoon of this invention can be used with any radiation source employedin vascular radiotherapy, which includes gamma radiation emittingsources and beta radiation emitting sources known in the art.

Continuing with reference to FIG. 13, two radio-opaque markers, a distalmarker 37 and a proximal marker 38, may be attached to the radiationsource lumen 22. The radio-opaque markers 37 and 38 are used forpositioning the interventional catheter 1 under fluoroscopy, as well asfor assisting the stepping (via manual or automatic means) of theradiation source 25 over the entire prescribed region of the vessel 16to be treated. The markers 37 and 38 are made of any materials known inthe art of radio-opaque markers, such as silver, gold, platinum,tungsten, that allow markers to become visible under fluoroscopy In oneembodiment, the radio-opaque markers (37, 38) are attached within thelimits of the balloon's treatment area 30. In one configuration, thedistal marker 37 is incorporated into the plug 24 of the source lumen22. In another configuration, radio-opaque markers (37, 38) may be partof a separate device (not shown) that is independent of the ballooncatheter assembly.

A soft tip 26 is attached to the distal end of the guidewire lumen 21 toimprove trackability and reduce trauma to the body vessel. The length ofthe soft tip 26 depends on the type of catheter design used, however,the length of the tip is generally in a range of approximately 0.5 mm to10 mm.

With reference to FIG. 13, the balloon 10 is attached to catheter shaft41 of the catheter assembly 2. The balloon proximal seal 29 ispositioned at a proximal end 44 of flexible catheter shaft 41, near theinflation/deflation port 33. The balloon distal seal 28 is positioned tothe catheter shaft 41 adjacent to the location where the radiationsource lumen 22 ends. In one embodiment, the balloon 10 and assembly 2are coupled using a laser bond technique. Bonds may also be done usingother balloon bonding techniques known in the art, such as thermal orultrasonic welds, adhesive welds, or other conventional means.

Multi-lumen Balloon Catheter Having a Balloon with or withoutCommunication Bores between Central and Outer Lumens and A GuidewireLongitudinally Extending Outside the Fluted Balloon Lumens

In FIGS. 27a-27 d, a fluted balloon radiation centering catheterassembly 1 for a catheter with a guidewire longitudinally extendingoutside the multi-lumen balloon is shown.

Referring to FIG. 27a, a multi-lumen fluted balloon radiation centeringcatheter assembly 1 with the balloon 10 in an inflated state is shown.The fluted balloon radiation centering catheter assembly 1 includes amulti-lumen balloon 10 and an interventional catheter 2. Interventionalcatheter 2 has a shaft disposed proximate the balloon 10. The balloon 10includes a plurality of inflatable outer lumens 11 disposed around acentral lumen 12, the plurality of outer lumens 11 integrally coupledwith the central lumen 12 so as to form the multi-lumen balloon 10. Theballoon 10 has a distal seal 28 and a proximal seal 29. Distal seal 28seals the plurality of distal ends 34 b of the balloon outer lumens 11to the catheter shaft 41 while the proximal seal 29 seals the pluralityof proximal ends 34 a of the balloon outer lumens 11 to the cathetershaft 41. The distal and proximal seals (28, 29) may each have a widthin a range of approximately 0.5 mm to about 5 mm.

Each of the outer lumens 11 takes the form of a “flute” (i.e., anelongated cylinder having tapered ends) when inflated by an inflationmedium 18 b (shown in FIG. 14 for this balloon catheter assembly). Afluted balloon configuration is shown in FIG. 17, which is arepresentative illustration of balloon configurations of this invention(as revealed in balloon catheter assemblies of FIGS. 1, 6, 10, 13 and 27a).

Continuing with reference to FIG. 27a, the catheter shaft includes aninner tubular member 41 having an inner lumen 41 a (shown in FIG. 27b).The catheter shaft 41 further includes a flexible elongate outer tubularmember 46. Elongate inner tubular member 41 extends coaxially within theelongate outer tubular member 46.

Still referring to FIG. 27a, two additional guidewire exits (45 b 1 and45 b 2) are notched (or cut out) along the catheter shaft (whichincludes the tubular member 41) to permit a guidewire 45 to extendlengthwise outside the multi-lumen balloon 10 (see FIG. 27b) from anexisting guidewire exit notch 45 b 3 to a guidewire exit notch 45 b 2.At the point of the guidewire exit notch 45 b 2, the guidewire 45 entersthe catheter shaft' tubular member 41, extends lengthwise through aportion of the shaft and then exits the shaft at the second guidewireexit notch 45 b 1l. The profile of the fluted balloon with standard RXconfiguration is {fraction (50/1000)} in. by {fraction (60/1000)} in.,while the profile of the fluted balloon without the guidewire lumen isabout {fraction (51/1000)} in.

Through this balloon catheter embodiment, the guidewire riding length isextended over the “tip RX” design. This design arrangement has a numberof benefits over prior art designs, including (a) maintaining themulti-lumen balloon profile for the “standard RX” design, (b) reducingthe profile of the balloon proximal seal, (c) allowing the borecommunication between the central lumen and the plurality of outerlumens for an improved centering of the radiation source, and (d)reduces radial shielding effect.

Balloon Treatment Area Markers

As described and shown in figures above, the multi-lumen ballooncatheters of this invention may include radio-opaque markers forpositioning the interventional catheter 1 under fluoroscopy, as well asfor assisting the stepping (via manual or automatic means) of theradiation source 25 over the entire prescribed region of the vessel 16to be treated. Generally, the markers include a distal marker 37 and aproximal marker 38. Markers 37 and 38 may be attached to the radiationsource lumen 22 by adhesive bonding. Markers may also be swaged onto theradiation source lumen.

In yet another embodiment, markers 37 and 38 may be attached directlyonto the fluted balloon using a sputtering or vapor deposition process.In this process, a marker material such as gold is deposited onto theballoon using any sputtering or vapor deposition techniques known in thefield. It should be noted that the marker material deposition is notlimited to a specific area of the multi-lumen balloon; the markermaterial may be deposited onto the central lumen of the balloon, aroundthe entire circumference of the multi-lumen balloon, or any otherballoon area desired.

The markers 37 and 38 may made of any materials known in the art ofradio-opaque markers, such as silver, gold, platinum, tungsten, thatallow markers to become visible under fluoroscopy. In one embodiment,the radio-opaque markers (37, 38) are attached within the limits of theballoon's treatment area 30.

Balloon Proximal Seal

A unique proximal seal geometry used to seal a multi-lumen flutedballoon to a catheter shaft and method for manufacturing same isdescribed. In one embodiment (described herein), the proximal sealgeometry is used to seal a four-lumen fluted balloon to a shaftcontaining both a radiation source lumen and a guidewire lumen. Inanother embodiment (not shown), where the radiation source is usedwithout a radiation source lumen, the proximal seal geometry is used toseal a four-lumen fluted balloon to a shaft containing only a guidewirelumen. In yet another embodiment (not shown), where the catheter type isa “tip RX” (i.e., the guidewire lumen does not pass through any of theballoon lumens), the proximal seal geometry is used to seal a four-lumenfluted balloon to a shaft containing only a radiation source lumen.

Referring to FIG. 18, a cross sectional view of a multi-lumen flutedballoon 10 for treating a body vessel 16 in the vascular system isshown. Balloon 10 includes a central lumen 12 and a plurality of outerlumens (or lobes) 11 disposed around the central lumen 12. The outerlumens 1 1 are integrally coupled with the central lumen 12 so as toform the multi-lumen balloon 10. Each of the balloon outer lumens 11 hasan inner radial length (or diameter) 18 and an outer diameter 15,defining balloon outer lumen walls 17. The walls 17 of balloon outerlumens 11 are made very thin to allow proper inflation and deflation ofouter lumens 11.

The multi-lumen balloon 10 is manufactured of balloon materials, such asPebax™, nylon, polyethylene, polyurethane, or polyester. Materials foruse in fabricating the multi-lumen balloon 10 of the present inventionare selected by considering the properties and characteristics (e.g.,softness, durability, low stiffness) required by angioplasty balloons,as well as considering properties necessary for successful balloonfabrication (e.g., balloon material compatible with other cathetermaterials and bonding process, material extruding well, etc.).

In the embodiment illustrated in FIG. 17, a radiation source lumen 22 isplaced into the central lumen 12 of the fluted multi-lumen balloon 10,the radiation source lumen 22 extending lengthwise through the centrallumen 12. A guidewire lumen 21 is also placed into one of the balloon'souter lumens 11 (third outer lumen 11 of the balloon is hidden in FIG.17), the guidewire lumen 21 extending lengthwise through the balloonouter lumen. The balloon outer lumen 11 containing the guidewire lumen21 is labeled the guidewire outer lumen. Both the radiation source lumen22 and the guidewire lumen 21 are manufactured as co-extrusions havingan inner layer made of a material such as polyethylene and an outerlayer made of a material such as Pebax, nylon, or Primacor.

A first mandrel 22 a is then inserted through the radiation source lumen22 and a second mandrel 21 a is inserted:through the guidewire lumen 21.It should be noted that if the catheter type does not require for aguidewire lumen 21 to extend through the multi-lumen balloon (forexample, a “tip RX” catheter type or a catheter assembly havingslideable distal and proximal seals, as discussed above), the secondmandrel 21 a may not be necessary and would not have to be insertedthrough one of the balloon outer lumens 11. For balloon catheterembodiments where a radiation source lumen is not used (i.e., aradiation source would be positioned directly within the balloon centrallumen during the intervascular radiotherapy procedure), the firstmandrel 22a may be inserted directly through the balloon central lumen12.

After the first mandrel 22 a is inserted through the radiation sourcelumen 22 and the second mandrel 21 a is inserted through the guidewirelumen 21, the two outer lumens 11 not occupied by the guidewire lumen 21are compressed so as to give the outer lumens 11 (and thus the balloonproximal seal) a more compact configuration. Note that FIG. 18 shows across-section of the outer lumens 11 shape before the outer lumens arecompressed. As part of the compressing operation, the proximal ends ofthe two outer lumens 11 are flattened (see FIG. 19a), thus formingflattened outer lumens.

If a more packed configuration is desired for the flattened outer lumens11, the ends 53 of the flattened outer lumens 11 are folded back overthemselves (see FIG. 19c), thus creating folded outer lumens. It isnecessary to fold the ends 53 of the flattened outer lumens 11 back overthemselves to ensure that there is enough balloon material outside ofthe inflation lumens 54 b, 55 b (shown in FIG. 20a, and discussed inmore detail below) of the outer lumens 11 to maintain the inflationpressure. Alternative folding patterns of the flattened outer lumens mayalso be used if there is ample thickness in the catheter outer member 46to ensure that the inflation lumens (54 b, 55 b) will not leak. In oneapproach, the flattened outer lumens 11 may be left in the flattenedprofile shown in FIG. 19a or both ends 53 of the outer lumens may befolded towards the guidewire outer lumen (i.e., the outer lumen 11containing the guidewire lumen 21) (see FIG. 19b). Folding the flattenedouter lumens 11 may be performed manually, using full automationtechniques, or using a combination of manual and automated sub-steps.

If the flattened outer lumens are folded manually, many differentapproaches may be taken. For example, to achieve the embodiment shown inFIG. 19b, the flattened outer lumens are folded by simply using thethumb and forefinger to push down (or up, depending on the up or downorientation of the guidewire outer lumen) the two flattened outerlumens. The embodiment shown in FIG. 19c is done by using a pair oftweezers to fold over the ends of each of the two flattened outer lumens(one side at the time) until the desired fold configuration is achieved.

After folding the flattened balloon outer lumens 11, a catheter outermember 46 is placed over the central lumen 12 (with radiation sourcelumen 22) and the guidewire outer lumen 11 (with the guidewire lumen21). The catheter outer member 46 also overlaps the two outer lumens 11of the multi-lumen balloon 10 not occupied by the guidewire lumen 21.The catheter outer member 46 may be manufactured from materials such asnylon, Pebax, polyurethane, etc.

Inflation lumen mandrels 54 a and 55 a are then inserted to form andmaintain individual lumens (54 b, 55 b) for inflation of the outerlumens 11. The inflation lumen mandrels (54 a, 55 a) are generallyinserted from the balloon distal end 28 (see FIG. 17), however, theinsertion of the inflation lumen mandrels may also be accomplished fromthe balloon proximal end 29.

The inflation lumen mandrels 54 a (shown in FIG. 20d) have a“football”-shape cross-section 54 aa to better contour with the shape ofthe outer member 46 and prevent leaking of the inflation medium 18through the inflation lumens 54 a. In current prior art balloon sealprocesses, which use mandrels having a straight edged configuration(such as a flattened round wire mandrel), seal leaking can occur becausethe “sharp” edges of the flattened round wire mandrels protrude out ofthe seal, thus causing the inflation medium to leak out of the seal.

Referring to FIG. 20d, the inflation lumen mandrels 54 a include a shaft54 a 1 having a substantially football-shaped cross section. The shaft54 a 1 has a solid center, however, it may also have a hollow center 54a 2 extending lengthwise therein. The “football” shaped inflation lumenmandrels 54 a are also symmetrical (i.e., they do not have a “front”,“back”, “top”, or a “bottom”) to eliminate any dependence on a specificorientation and for ease of use during the manufacture of the proximalseal. The dimensions (i.e., length and cross-section “diameter”) of theinflation lumen mandrels 54 a vary depending for example, on thediameter of the balloon lumens, the type of material the mandrel is madeof, etc.

Referring to FIGS. 20a-20 c, FIG. 20a shows a cross-section view of thecompleted balloon proximal seal showing the inflation lumens 54 bcreated by the “football” shaped inflation lumen mandrels 54 a for thetwo outer lumens not occupied by the guidewire lumen, and the inflationlumen 55 b created by the flattened round wire inflation lumen mandrel55 a for the guidewire lumen 21. The flattened round wire inflationlumen mandrel 55 a can be replaced with a “football” shaped inflationmandrel 56 a (see FIG. 20b) or a triangular shaped mandrel 56 b (seeFIG. 20c). Following the insertion of the first and second mandrels (21a, 22 a) to retain the radiation source lumen 22 and the guidewire lumen21, and the inflation lumen mandrels (54 a, 55 a) to retain theinflation lumens (54 b, 55 b), the proximal end of the multi-lumenfluted balloon 10 is bonded to the distal end of the catheter outerlumen 46.

For the embodiment shown in FIG. 20a, a square-wave laser pattern bondis used to bond the outer member 46 to the balloon 10. A heat shrinktube 57 b (shown in FIG. 21c) is temporarily used during the square-wavelaser bond process. The heat shrink tube 57 b is positioned over theballoon catheter “proximal seal assembly”, which includes the proximalend of the multi-lumen balloon (with the radiation source lumen and theguidewire lumen if catheter assembly so requires it), the distal end ofthe catheter outer member, and all the mandrels. When heat from thelaser beam is applied onto the heat shrink tube 57 b, the tubecompresses radially onto the balloon catheter proximal seal assembly.The shrink tube compression causes the materials of the balloon proximalend and the outer member distal end to closely fuse together, creating aleak-tight balloon proximal seal. The heat shrink tube is then removed.It should be noted that the heat shrink tubing may be substituted withheat shrink materials having other shapes, such as heat shrink sheaths,etc.

The shrink tubing is made from materials known in the art of catheterballoon manufacture. For one embodiment, the shrink tubing has adiameter 57 b 1 of 2.5 mm, however, the diameter 57 b 1 of the shrinktubing to be used depends on a number of factors, such as the size ofthe balloon catheter to be manufactured, the degree of folding performedon the balloon outer lumens, whether the balloon catheter includes aradiation source lumen and/or a guidewire lumen extending through theballoon, etc.

In the present invention, laser bonding techniques, such as laserbonding using a square-wave laser pattern (or design) are desired.However, bonds may also be done using other balloon bonding techniquesknown in the art, such as thermal bonding, ultrasonic bonding, adhesivebonding (for example using a glue-type material), or other conventionalmeans.

Following the laser bonding of the outer member 46 to the balloon 10,the inflation lumen mandrels 54 a and 55 a are removed from the balloonproximal seal assembly.

Given the “egg-shape” like configuration, the completed balloon proximalseal cross-section may have a “small diameter” 46 d 1 (i.e., measuredhorizontally across the seal) in the range of approximately 35-50 mm,while the “large diameter” 46 d 2 (i.e., measured vertically across theseal) in the range of approximately 60-80 mm. In one embodiment, theproximal seal cross section has a “small diameter” 46 d 1 of about 47 mmand a “large diameter” 46 d 2 of about 62 mm.

“Football”-shaped Mandrels

As mentioned above, “football”-shaped mandrels are used in themanufacture of the multi-lumen balloon centering catheter proximal seal.Mandrels having a “football”-shape cross-section are not just limited tothe manufacture of centering catheters. “Football”-shape cross sectionmandrels can also be used in fabricating other medical interventionaldevices, such as atherectomy devices, delivery systems (stent or drug)and other devices requiring a tight seal configuration.

Referring to FIG. 20d, a “football”-shape cross section mandrel includesa shaft 54 a 1 having a substantially football-shaped cross section. Theshaft 54 a 1 has a solid center, however, it may also have a hollowcenter 54 a 2 extending lengthwise therein. The “football”-shapedmandrel shaft 54 a 1 is made to be symmetrical (i.e., the shaft does nothave a “front”, “back”, “top”, or a “bottom”) to eliminate anydependence on a specific orientation and for ease of use. The“football”-shaped mandrel 54 a may be manufactured out of metal, of anon-stick material such as Teflon, or of any non-metal materials thatwill not melt at the same temperature as the materials used formanufacturing the particular medical device. The dimensions (i.e.,length and cross-section “diameter”) of the “football”-shaped mandrel 54a vary depending for example, on the diameter of the balloon lumens, thetype of material the mandrel is made of, etc. In one embodiment, the“football”-shaped mandrel 54 a has a “large diameter” 54 aa 1 (see FIG.20d) in a range of approximately {fraction (4/1000-30/1000)} in. to a“small diameter” 54 aa 2 in a range of approximately {fraction(2/1000-20/1000)} in.

Balloon Distal Seal

A unique balloon distal seal geometry used to seal a multi-lumen flutedballoon to a catheter shaft is described. The present invention providesa solution to the problem of bundling together a multi-lumen shaft atthe distal end of a multi-lumen balloon without using additionalmaterials that could increase the stiffness of the distal tip. Theballoon distal seal is completed following the completion of the balloonproximal seal (as discussed above).

In one embodiment (described herein), the balloon distal seal geometryis used to seal a four-lumen fluted balloon to a shaft containing both aradiation source lumen and a guidewire lumen extending through theballoon lumens. It should be noted that for a “tip RX” catheter type(i.e., where the guidewire lumen does not extend through any of theballoon lumens), the balloon distal seal geometry is used to seal afour-lumen fluted balloon to a shaft containing a radiation source lumenand a short guidewire lumen distally positioned to the multi-lumenballoon. In another embodiment (not shown), where the radiation sourceis used without a radiation source lumen, the balloon distal sealgeometry is used to seal a four-lumen fluted balloon to a shaftcontaining only a guidewire lumen.

Referring to FIG. 18, a cross sectional view of a multi-lumen flutedballoon 10 for treating a body vessel 16 in the vascular system isshown. Balloon 10 includes a central lumen 12 and a plurality of outerlumens (or lobes) 11 disposed around the central lumen 12. The outerlumens 11 are integrally coupled with the central lumen 12 so as to formthe multi-lumen balloon 10. The multi-lumen balloon 10 is manufacturedof balloon materials, such as Pebax™, nylon, polyethylene, polyurethane,or polyester.

Referring to FIG. 17, a radiation source lumen 22 is placed into thecentral lumen 12 of the fluted multi-lumen balloon 10, the radiationsource lumen 22 extending lengthwise through the central lumen 12. Aguidewire lumen 21 is also placed into one of the balloon's outer lumens11 (third outer lumen 11 of the balloon is hidden in FIG. 17), theguidewire lumen 21 extending lengthwise through the balloon outer lumen.The balloon outer lumen 11 containing the guidewire lumen 21 is labeledthe guidewire outer lumen. Both the radiation source lumen 22 and theguidewire lumen 21 are manufactured as co-extrusions having an innerlayer made of a material such as polyethylene and an outer layer made ofa material such as Pebax, nylon, or Primacor.

Referring to FIG. 21a, a completed balloon distal seal 28 isillustrated. As discussed above, the balloon distal seal is completedfollowing the completion of the balloon proximal seal.

To complete the distal seal 28 for a multi-lumen balloon radiationcentering catheter, the following sub-steps are performed. First, afirst source mandrel 22 a is inserted into the radiation source lumen 22and a first guidewire mandrel 21 a is inserted into the guidewire lumen21. Mandrels 22 a and 21 a form a first set of source and guidewiremandrels. In one embodiment of this invention, the first source mandrel22 a has a diameter of 0.0225 in., while the first guidewire mandrel 21a has a diameter of 0.017 in. The diameters of the first source andguidewire mandrels may vary depending on a number of factors, such asthe type of source used, the size of the multi-lumen balloon wheninflated (e.g., 2 mm, 3 mm balloon overall diameter), etc.

Next, a soft tip material 26 is placed over the first guidewire mandrel21 a so as to overlap the guidewire lumen 21. The soft tip material 26is attached to the distal end 27 of the guidewire lumen 21 to improvetrackability and reduce trauma to the body vessel. The length of thesoft tip 26 depends. on the. type of catheter design used. However, whencompleted, the length of the soft tip 26 is generally in a range ofapproximately 0.5 mm to 10 mm. The soft tip is manufactured frommaterials generally known in the field of balloon angioplasty.

Next, to prepare the balloon distal seal for laser bonding, a firstshrinkable material, such as a shrink tube 57 b is positioned over theballoon distal seal sub-assembly. The sub-assembly includes the distalend of the multi-lumen balloon (with the radiation source lumen and theguidewire lumen, if catheter assembly so requires it) and both mandrels(21 a, 22 a). The distal seal sub-assembly is then fastened using a hotbox device (not shown). The balloon distal end 34 b is then sealed usinga laser device (not shown). It should be noted that the heat shrink tube57 b is only temporarily used during the laser bond process.

When heat from the laser beam is applied onto the heat shrink tube, thetube compresses radially onto the balloon catheter distal seal assembly.The shrink tube compression causes the materials of the balloon distalend 34 b to closely fuse together, creating a leak-tight balloon distalseal. The heat shrink tube 57 b is then removed.

It should be noted that the heat shrink tube may be substituted withheat shrink materials having other shapes, such as heat shrink sheaths,etc. The shrink tube 57 b is made from materials known in the art ofcatheter balloon manufacture. For one embodiment, the shrink tube 57 bhas a diameter 57 b 1 of 2.5 mm, however, the diameter of the shrinktube to be used depends on a number of factors, such as the size of theballoon catheter to be manufactured, the degree of folding performed onthe balloon outer lumens, whether the balloon catheter includes aradiation source lumen and/or a guidewire lumen extending through theballoon, etc.

After removing the first shrink tube 57 b, a tip jacket 57 is placedover both the guidewire lumen 21 and radiation source lumen 22. A secondshrinkable material, such as a shrink tube 57 c is placed over the tipjacket 57. The second shrink tube 57 c is made from materials known inthe art of catheter balloon manufacture. For one embodiment, the shrinktubing 57 c has a diameter 57 b 1 of 2.0 mm, however, the diameter mayrange in a range of approximately 1.0-3.0 mm. The distal sealsub-assembly (with the tip jacket 57) is then sealed using a laserdevice (not shown).

The multi-lumen fluted balloon distal seal sub-assembly is laser sealedusing a conventional helical-wave laser design. In the presentinvention, laser sealing or bonding techniques such as the square-wavelaser design may be desirable. However, bonds may also be done usingother balloon bonding techniques known in the art, such as thermal orultrasonic welds, adhesive bonds (for example glue), or otherconventional means.

Following the laser bonding of;the tip jacket 57, the second shrinktubing 57 c is removed. The first set of source and guidewire mandrels(22 a, 21 a) is then replaced with a second set of source and guidewiremandrels (22 aa, 21 aa) having smaller diameters than mandrels 22 a and21 a. In one embodiment of this invention, the second source mandrel 22aa has a diameter of 0.0205 in., while the second guidewire mandrel 21aa has a diameter of 0.016 in. The diameters of the second source andguidewire mandrels may vary depending on a number of factors, such asthe type of source used, the size of the multi-lumen balloon wheninflated (e.g., 2 mm, 3 mm balloon overall diameter), etc.

Once the source and guidewire mandrels are replaced withsmaller-diameter mandrels, a tip-forming sheath 57 a (shown in FIG. 21b)is placed over the laser-sealed tip jacket 57. Using the tip-formingsheath 57 a, a guidewire soft tip (shown in FIGS. 1, 6, 10, and 13) isformed using by placing the balloon seal sub-assembly into a hot box(not shown). At the completion of the distal seal 28, the second sourcemandrel 22 aa and the second guidewire mandrel 21 aa are removed fromthe balloon seal sub-assembly.

Alternative Source Mandrel Designs for Distal Seal

The source mandrels presented above refer to a mandrel design having acircular cross-section. However, the circular cross-section design forthe source mandrels may be substituted by using two additional sourcemandrel designs: (1) a tapered-shape mandrel, and (2) a ramped-shapemandrel. These two embodiments of this invention are now discussed

Tapered Mandrel

Referring to FIG. 21d, a tapered mandrel is formed by having a gradualtaper of one end of the mandrel (22 a or 22 aa) while keeping the roundcross-sectional shape concentric to the mandrel. The tapered mandrel hasa gradual taper length 21 a 1 that may vary from 0 cm (i.e., flat endedmandrel) to a taper length 21 a 1 of 10 cm. This gradual taper shapesthe end of the source lumen 22 to direct the radiation source (such as awire) directly at center of the lumen.

Ramped Mandrel

Referring to FIG. 21e, a ramped mandrel (22 a or 22 aa) is shown. In theramped mandrel design, a round is first made to one end of the mandrel.Then a flat ramp is cut into the same end of the mandrel on one side(see FIG. 21e). The ramped mandrel has a ramp length 22 a 2 that mayvary from 0 cm (i.e., flat ended mandrel) to a ramp length 22 a 2 of 5cm. This ramped feature shapes the end of the source lumen to direct thesource wire slightly downwards and away from exiting through the top ofthe lumen.

Method of Manufacture

Multi-Lumen Tubing

Referring to FIGS. 22a-25 a, the multi-lumen fluted balloon 10 of thisinvention is fabricated by blowing a multi-lumen tubing 60 created usingan extrusion process. The multi-lumen extruded tubing 60 has a tubingbody 61, a central lumen 62, and at least one outer lumen 63 disposedadjacent to the central lumen 62. Generally, a plurality of outer lumens63 are disposed adjacent to the central lumen 62. The outer lumen 63 iscoupled with the central lumen 62 by a shared wall 67 (as shown in FIGS.22a-25 a). In one embodiment, the multi-lumen tubing 60 has three outerlumens 63 disposed adjacent to the central lumen 62.

Referring the FIGS. 23a and 24 a, in one embodiment of the presentinvention, the multi-lumen tubing 60 has at least one outer lumen 63disposed adjacent to the central lumen 62. The outer lumen 63 is coupledwith the central lumen 62 by a shared wall 67. The multi-lumen tubing 60further includes an undercut radius region 65 disposed between thecentral lumen 62 and the outer lumen 63. The shared wall 67 may have ashared wall thickness 67 b in the range of approximately 50%-200% of theouter lumen wall thickness 67 c (as shown in FIG. 23a). In oneembodiment, the shared wall 67 may have a shared wall thickness 67 b inthe range of approximately 80%-120% of the outer lumen wall thickness 67c (as shown in FIG. 24a).

Referring to FIG. 22a, in another embodiment of the present invention,the multi-lumen tubing 60 has at least one outer lumen 63 disposedadjacent to the central lumen 62. The outer lumen 63 is coupled with thecentral lumen 62 by a shared wall 67. The multi-lumen tubing 60 includesa fillet radius region 66 instead of the undercut region 65 shown in theembodiments of FIGS. 23a and 24 a. The fillet radius region 66 isdisposed between the central lumen 62 and the outer lumens 63. Theshared wall 67 may have a shared wall thickness 67 b in the range ofapproximately 50%-200% of the outer lumen wall thickness 67 c. In oneembodiment, the shared wall 67 may have a shared wall thickness 67 b inthe range of approximately 80%-120% of the outer lumen wall thickness 67c (as shown in FIG. 23a).

Referring to FIG. 25a, in a third embodiment of the present invention,the multi-lumen tubing 60 includes a standoff region 64 disposed betweenthe central lumen 62 and the outer lumens 63. In this configuration, thestandoff region 64 is the same as the shared wall 67 (i.e., the standoffregion 64 has the same shape and length as the shared wall 67). Thestandoff region 64 may have a standoff region thickness 67 bb in therange of approximately 50%-200% of the outer lumen wall thickness 67 c.In one embodiment, the standoff region 64 may have a standoff regionthickness 67 bb in the range of approximately 80%-120% of the outerlumen wall thickness 67 c (as shown in FIG. 25a).

The multi-lumen tubing 60 of the present invention may have an overalldiameter 68 in the range of approximately {fraction (20/1000)} in. and{fraction (50/1000)} in. In one embodiment of this invention, themulti-lumen tubing 60 may have an overall diameter 68 in a range ofapproximately about {fraction (34/1000)} in. to {fraction (48/1000)} in.

The central lumen 62 of the multi-lumen tubing 60 may have an innerdiameter (69 a-69 d, as shown in FIGS. 22a-25 d) in a range ofapproximately about {fraction (7/1000)} in. to {fraction (13/1000)} in.In one embodiment of this invention, the central lumen 62 of themulti-lumen tubing 60 has an inner diameter of about {fraction(10/1000)} in.

The outer lumens 63 of the multi-lumen tubing 60 may have an outer lumenwall thickness 67 c in a range of approximately {fraction (2/1000)} in.to {fraction (8/1000)} in. In one embodiment of this invention, theouter lumens 63 may have an outer lumen wall thickness 67 c in a rangeof approximately {fraction (3.5/1000)} in. to {fraction (6/1000)} in.

The multi-lumen tubing 60 is manufactured using balloon materials, suchas resin, Pebax™, nylon, polyethylene, polyurethane, or polyester.Materials for use in fabricating the. multi-lumen extrusion tubing 60 ofthe present invention are selected by considering the properties andcharacteristics (e.g., softness, durability, low stiffness) required byangioplasty balloons, as well as considering properties necessary forsuccessful balloon fabrication (e.g., balloon material compatible withother catheter materials and bonding process, material extruding well,etc.).

Multi-Lumen Tubing—Method of Manufacture: Extrusion

FIG. 26 is a flow chart illustrating the steps of fabricating amulti-lumen extruded tubing of one embodiment of the present invention,such as the multi-lumen extruded tubing for the radiation centeringcatheter shown in FIGS. 1, 6, 10, and 13.

Referring to FIG. 26, the first step in the extruded tubing manufactureprocess is to select an appropriate material from which the extrudedtubing (and thus the balloon) will be manufactured (step 100). Recallthat the multi-lumen extruded tubing is made of balloon materials knownin the art of balloon angioplasty, such as Pebax™, nylon, polyethylene,polyurethane or polyester. Generally, any resin-type material may beused to manufacture the multi-lumen extruded tubing. Materials for usein fabricating the multi-lumen extruded tubing of the present inventionare selected by considering the properties and characteristics (e.g.,softness, durability) required by angioplasty balloons, as well asconsidering properties necessary for successful balloon fabrication(e.g., balloon material compatible with other catheter materials andbonding process, material extruding well, etc.).

At step 200 in the multi-lumen extruded tubing fabrication process, theresin material is placed into a hopper (or a similar. purposereceptacle) and is then gradually brought to a molten state.

The next three steps (Steps 300, 400, and 500) are performedconcurrently during the multi-lumen extruded tubing manufacture process.In Step 300, the molten resin material is run through a tip and dieassembly such that at least one multi-lumen shaft is formed. As part ofStep 400, a pressurized medium (such as air or other gas) is appliedinto each of the lumens of the multi-lumen shaft (or the plurality ofsingle lumen shafts) formed as part of Step 300 to maintain and/orcontrol the inner diameter of the lumens (or bores) 63 formed lengthwisealong the centerline of the shaft (or along a centerline of each of theplurality of shafts). If a pressurized gas is used, the pressurized gasapplied to the plurality of resin material shafts may done at a pressurein the range of approximately 0-30 inches of water. In one embodiment,the pressurized gas applied to the plurality of resin material shafts isat a pressure of 2 inches of water.

Step 500 includes pulling the shaft (or depending on the extrusion dieconfiguration, a plurality of shafts) away from the extrusion die (usinga puller or similar device) so as to form the multi-lumen extrudedtubing having the desired lumen inner diameter, lumen wall thickness,shared wall thickness, outer tubing shape, etc. Pulling the plurality ofshafts away from the extrusion die (Step 500) may be done while theresin material is at a melt temperature in the range of about 370° F. to440° F. In one embodiment, pulling the plurality of shafts away from theextrusion die is done while the resin material is at a melt temperaturein the range of about 380° F. to 410° F. Pulling the plurality of resinmaterial shafts away from the extrusion die may be done at a pullingrate of about 25-100 feet per minute. In one embodiment, pulling theplurality of resin material shafts away from the extrusion die is doneat a pulling rate of about 45-65 feet per minute.

For extrusion die configurations that permit a plurality of shafts to beformed instead of a single shaft (as discussed below), Step 500 includespulling the plurality of shafts away from the extrusion die so as tocause the plurality of shafts to fuse together lengthwise into themulti-lumen extrusion tubing having a central lumen and at least oneouter lumen disposed adjacent to the central lumen.

Referring to FIGS. 22b-25 b, several embodiments of a tip and dieassembly of the present invention are shown. Each tip and die assemblyincludes an extrusion die (shown as 70, 170, 270, 370 in FIGS. 22b-25 b)and a plurality of extrusion tip hypo-tubes (identified as: 71 a, 171 a,271 a, 371 a in the figures) through which a pressurized medium (such asair, an inert gas, liquid, etc.) is introduced into the shaft's lumen tomaintain and/or control the inner diameter of the lumen. The extrusiondie may have a single common exit hole (item 76 in FIG. 22b and item 376in FIG. 25b) or a plurality of exit holes (items 171, 172 in FIG. 23band items 71, 72 in FIG. 24b). The hypo-tubes may take the form ofmandrels (items 271 a, 171 a, 71 a, and 371 a in FIGS. 22b-25 b) havinga bore extending lengthwise through the center of the mandrels.

Continuing with reference to FIG. 22b, the extrusion die 270 is used inthe manufacture of the multi-lumen extruded tubing 60 shown in FIG. 22a.The extrusion die 270 includes a single common exit hole 76 having aprofile such that a multi-lumen extruded tubing 60 with a fillet radiusregion 66 disposed between the central lumen 62 and the plurality ofouter lumens 63 is formed. The extrusion die 270 may be manufactured outof a metal, a hard plastic, or any other type of material used inmedical extrusion tubing processes. Using a die with a single commonexit hole simplifies the overall tubing extrusion process, thuspermitting a multi-lumen single shaft to be more easily manufactured.

Referring to FIG. 23b, in a second embodiment of this invention, theextrusion die 170 is used in the manufacture of the multi-lumen extrudedtubing 60 shown in FIG. 23a. The extrusion die 170 has at least oneouter exit hole 171 disposed around a central exit hole 172. The outerexit hole 171 may be positioned at various distances 175 from thecentral exit hole 172. It may be desirable to place the outer exit hole171 as close as possible to the central exit hole 172 in order tominimize the amount of resin material of the shared wall thickness 67 b(shown in FIG. 23a). Having less resin material as part of the sharedwall permits the multi-lumen tubing to blow better during the balloonforming process and ultimately leads to a less stiff balloon. Theextrusion die 170 may be manufactured out of a metal, a hard plastic, orany other type of material used in medical extrusion tubing processes.

Referring to FIG. 24b, in a third embodiment of this invention, theextrusion die 70 is used in the manufacture of the multi-lumen extrudedtubing 60 shown in FIG. 24a. The extrusion die 70 includes at least oneouter exit hole 71 disposed around to a central exit hole 72. The outerexit hole 71 has a substantially flat shape across a part 73 of aperiphery where the outer exit hole 71 is disposed adjacent to thecentral exit hole 72. The central exit hole 72 also has a substantiallyflat shape across a part 74 of a periphery where the central exit hole72 is disposed adjacent to the outer exit hole 71.

The extrusion die 70 may be configured so that the outer exit hole 71could be positioned at various die region thicknesses (or distances) 75on the die region between the central exit hole 72 and outer exit hole71. The die region thickness 75 may range from 0 in. to {fraction(10/1000)} in. In one embodiment, the die region thickness 75 betweenthe central exit hole 72 and the outer exit hole 71 is about {fraction(5/1000)} in. It may be desirable to keep the die region thickness 75 toa thickness width such that when formed, the shared wall thickness 67 bof the multi-lumen 60 is approximately equal to the outer lumen wallthickness 67 c (see FIG. 24a). Having a shared wall thickness in therange of approximately 80% and 120% of the outer lumen wall thickness 67c minimizes the resin material of the shared wall and permits themulti-lumen tubing to blow better during the balloon forming process andultimately leads to a less stiff balloon. The extrusion die 70 may bemanufactured out of a metal, a hard plastic, or any other type ofmaterial used in medical extrusion tubing processes.

Referring to FIG. 25b, in a fourth embodiment of this invention, theextrusion die 370 is used in the manufacture of the multi-lumen extrudedtubing 60 shown in FIG. 25a. The extrusion die 370 includes a singlecommon exit hole 376 having a profile such that a multi-lumen extrudedtubing 60 with at least one standoff region 64 disposed between thecentral lumen 62 and the outer lumens 63 is formed (see FIG. 25a). Theextrusion die 370 may be manufactured out of a metal, a hard plastic, orany other type of material used in medical extrusion tubing processes.Using a die with a single common exit hole and having a profile with atleast one standoff region minimize the amount of resin material betweenthe central lumen 62 and plurality of outer lumens 63 (shown in FIG.25a). Having less resin material permits the multi-lumen tubing 60 toblow better during the balloon forming process and ultimately leads to aless stiff balloon. Furthermore, using a die with a single common exithole simplifies the overall tubing extrusion process, thus permitting amulti-lumen single shaft to be more easily manufactured.

The next step in the fabrication process, Steps 610 and 620, is to formthe final balloon shape with multiple lumens. This is achieved byplacing the multi-lumen extruded tubing obtained after completion ofSteps 300-500 into a steel cylinder that is configured to have theappropriate shape of the final balloon.

Once the multi-lumen balloon is formed and shaped to the desireddimensions and configurations, the next steps include preparing theballoon and catheter assembly for the balloon proximal seal (Step 710)and performing the balloon proximal seal (Step 720). Step 810 includespreparing the balloon and catheter assembly for the balloon distal seal,while Step 820 includes performing the balloon distal seal.

In one embodiment of the present invention, laser bonding techniques areused to perform the proximal and distal seals. However, any seal bondingtechniques known in the art of manufacture of angioplasty ballooncatheters may be employed to achieve the seals.

Multi-Lumen Tubing—Alternate Method of manufacture: Dip Coating

An alternate method of manufacture of the multi-lumen balloon is byusing a “Dip Coating” process. A description of this process and how themulti-lobed, multi-lumen balloon is made is presented herein.

First, a “mandrel” is obtained. The mandrel includes component elements(such as pins) that are sized and arranged such that they define thelumens (i.e., interior void spaces) of the intended multi-lumen balloon.

Next, the physical balloon elements (i.e., balloon lumens, thickness ofballoon walls, etc.) are defined by applying a thin film of apre-selected polymer (analogous to applying paint) on and about the pin.In one embodiment, the application of the thin film polymer is achievedby immersing the mandrel into a bath of the desired polymer. The polymermay be any polymer with properties that would lend themselves to dipcoating such as the ability to go into solution or suspension withsubsequent recovery of adequate film properties. Materials already usedin this manner are for example: poly-urethanes, siloxanes or silicones,and latexes.

The thickness of the film (balloon wall) may be controlled by suchfactors as the viscosity of the bath solution and/or the number of timesthe mandrel is dipped into the solution. The “carrier” or “solvent” isthen driven off (evaporated) by normal means such as time in ambient airor forced convection with or without added heat.

The balloon, if appropriate to the polymer selected, may be furtherprocessed to impart enhanced or additional properties such asirradiation to increase cross-linking. This can be achieved eitherbefore or after removing from the mandrel as appropriate to the materialand/or properties and/or process.

In the next step, the film that is the balloon is then “stripped off”the mandrel through any appropriate means such as: using compressed airported through the pins that make up the mandrel, swelling the balloonmaterial with some other solvent which frees the balloon material fromthe mandrel and this solvent is then driven off returning the balloon tothe original dimensions, mechanically stripping off the balloon, etc.

Finally, the balloon is trimmed and prepped as necessary for integrationwith the remaining catheter components.

A multi-lumen balloon for use in a fluted balloon centering catheter andmethod for providing the same has been described. Although specificembodiments, including specific parameters, methods, and materials havebeen described, various modifications to the disclosed embodiments willbe apparent to one of ordinary skill in the art upon reading thisdisclosure. Therefore, it is to be understood that such embodiments aremerely illustrative of and not restrictive on the broad invention andthat this invention is not limited to the specific embodiments shown anddescribed.

What is claimed is:
 1. A method for making multi-lumen tubing, themethod comprising: pushing a molten resin material through a tip and dieassembly such that a plurality of resin material shafts are formed, thetip and die assembly including an extrusion die and a plurality ofmandrels, wherein the extrusion die has at least one outer exit holedisposed adjacent to a central exit hole; applying a pressurized mediumto the plurality of resin material shafts so as to maintain a lumenrunning lengthwise along the plurality of resin material shafts; andpulling the plurality of resin material shafts away from the extrusiondie so as to cause the plurality of resin material shafts to fusetogether lengthwise into the multi-lumen extrusion tubing having acentral lumen and at least one outer lumen disposed adjacent to thecentral lumen.
 2. The method of claim 1, wherein the at least one outerexit hole has a substantially flat shape across a part of a peripherywhere the at least one outer exit hole is disposed adjacent to thecentral exit hole.
 3. The method of claim 1, wherein the central exithole has a substantially flat shape across a part of a periphery wherethe central exit hole is disposed adjacent to the at least outer exithole.
 4. The method of claim 1 wherein said pulling the plurality ofresin material shafts away from the extrusion die is done while theresin material is at a melt temperature in the range of about 370° F. to440° F.
 5. The method of claim 1 wherein said pulling the plurality ofresin material shafts away from the extrusion die is done while theresin material is at a melt temperature in the range of about 380° F. to410° F.
 6. The method of claim 1 wherein the resin material is nylon. 7.The method of claim 1 wherein the resin material is polyethylene.
 8. Themethod of claim 1 wherein the resin material is polyester.
 9. The methodof claim 1 wherein the pressurized medium comprises a pressurized gas.10. The method of claim 9 wherein the pressurized gas applied to theplurality of resin material shafts is applied at a pressure of in arange of approximately 0-30 inches of water.
 11. The method of claim 9wherein the pressurized gas applied to the plurality of resin materialshafts is applied at a pressure of 2 inches of water.
 12. The method ofclaim 1 wherein the pressurized medium comprises air.
 13. The method ofclaim 1 wherein said pushing a molten resin material through anextrusion die and said applying a pressurized fluid to the plurality ofresin material shafts so as to maintain a lumen are performedconcurrently.
 14. The method of claim 1 wherein said pulling theplurality of resin material shafts away from the extrusion die is doneat a pulling rate of about 25-100 feet per minute.
 15. The method ofclaim 1 wherein said pulling the plurality of resin material shafts awayfrom the extrusion die is done at a pulling rate of about 45-65 feet perminute.
 16. The method of claim 1 wherein the at least one outer lumenhas an outer lumen wall thickness in a range of approximately0.0035-0.006 in.
 17. The method of claim 1 wherein the multi-lumentubing has an overall diameter in a range of approximately {fraction(34/1000)} in. to {fraction (48/1000)} in.